This is a character that has undergone so many changes, it seems hard to keep up with her. She is what the Marvel Comic Universe calls a mutant, that is a person born with special abilities that "normal" humans don't have. These "extra powers" however don't usually manifest themselves until puberty. Rachel's mutant abilities are telepathy (the ability to read the minds of others and influence them), telekinesis (the ability to move objects with pure mental power), and projecting her mind or the mind of another through time into someone's body. All these powers she was born with and don't have anything to do with the Phoenix Force which I will explain later. Her parents, Scott and Jean Summers, are also mutants themselves.

Ok, are you with me so far? Good, because it gets much more complicated. Rachel came from the future into our present to see if she could change the past so that her future wouldn't be so horrible. Without getting too wordy, I'll just say that in the future from which Rachel comes, mutants are hunted down and imprisoned or killed. She became (against her will) a slave to those who were trying to get rid of all mutants. They programmed her into what they called a "hound" and permanently tatooed her face so she wouldn't forget it! She was forced to track down mutants, including her own friends, so that they could be captured. Needless to say, this whole experience was very traumatic on our young Rachel. She later broke free from her "masters" and used her telepathy to hide the hound scars on her face.

At some later point she and Kate Pryde who were imprisoned decided to sent Kate 's mind back into the past (Rachel can do that) into her younger self to prevent the assasination of a Senator that seemed to be on the side of mutants.  They believed that if this Senator had lived that their future might have turned out much better instead of the nightmare that it really was. Well unfortunately this didn't work because when Kate went back to her future, nothing had changed.  On the way back however, the Phoenix Force presented itself to Kate (without Rachel's knowledge) and made an agreement with her.  The Phoenix Force would send Rachel back into the past so that she could live a better life and at the same time her memories of the hell she went through would be clouded to spare her pain. All Kate would have to do is say the code words: "Dark Phoenix" . The reason the Phoenix did this was because it saw everything Rachel went through in life and had compassion on her.  Why to this one particular soul you ask?  The Phoenix Force at one time had lived as Jean Grey for a time (Rachel's mother) so I guess her motherly instincts from being a human kicked in. So now the plan was in place and all without Rachel's knowledge.  Kate and Rachel went on a suicide mission to destroy an enemy base and before anything could happen to them Kate said the words, "Dark Phoenix" and instantly the Phoenix Force boosted Rachel's powers to send her body as well as her mind into the past.

Click to see Days of the Future Past

So now here she is in the past. Only one problem; it isn't her past! She crossed over into a different time line completely! Almost identical to ours, but she soon discovers the differences.  Her father is married to some woman named Madeline and Jean Grey, her mother, is supposedly dead when Rachel wasn't even born yet! Talk about trying not to have a nervous breakdown! Don't worry though, because later it is discovered that Jean is actually alive after all. Whew, what a relief!

For a while, Rachel stays with the X-Men and has some adventures with them. It is during this time that she embraces the powers of the Phoenix Force. What a power boost. She now has access to a cosmic force that permeates the entire universe. It manifests itself by displaying a giant fiery bird behind her. One time she let the power go to her head when she tried to kill this evil mutant named Selene and had to have Wolverine put her in her place.  Of course he didn't have to be so rough on her because what he did was gut her with his claws!  Yeouch!  Are you crazy Logan???  Click on the image to see more.  She doesn't even think she's going to make it when this extra-dimensional being named Spiral convinces her to go with her with promises to help her.  Rachel was so upset that she agreed to go with her not knowing that it was a trap to use her as entertainment in the wacky world of Mojo an insane ruler from another dimension.

After a while Rachel tries to escape from that dimension and back into ours but Mojo sends out these creatures called Warwolves to retrieve her.  As all this is happening, some of her friends were dreaming about her being chased by these creatures and tried to help her escape, not realizing at first that this was happening in reality.  In the end Rachel comes back to this dimension with her friend's help and they decide that since they work so well together that they would form a new super hero team called Excalibur.  This new team which was based in England consisted of Rachel a.k.a. Phoenix, Nightcrawler, Shadowcat, Captain Britain and Meggan.

During this time she  is sort of on a quest to find her purpose in life.  She still couldn't understand why the memories of her past seemed so unclear.  She eventually realized however that the less she used the power of the Phoenix Force, the clearer her memories became so she then tries to avoid using it.  One day however she has no choice but to use that power to save her friends and the world from an evil being called Necrom who wanted to steal the power of the Phoenix from Rachel.  They had a battle of battles out in space and Necrom was winning.  Rachel didn't know what to do but then thought she would give him what he wanted just not in the way he wanted.  She told him that since he wanted it so bad that she'd give it to him and at first he thought he was victorious but Rachel's plan was to shove it down his throat so hard that he wouldn't be able to contain it and her plan worked.  Necrom was destroyed from the power overload.

 However, Rachel's mind was destroyed in the battle and as a result her union with the Phoenix was broken .  Then the Phoenix Force realized that it was separated from Rachel and sort of had an arguement with "Death" itself.  As a result, the Phoenix realized that it could not continue to exist in Rachel's body as it was and would have to free Rachel from their bond.  The Phoenix then slowly heals Rachel and explains to her that she would still be able to tap into the Force but that it had to return to it's formless state of cosmic force in the universe.  As a result, Rachel gets all her memories back and finally feels whole for the first time since leaving the future.  She reappears to her friends and has a wonderful reunion.    

Upon returning to her friends and with her memories fully intact she decides to return to the future (alone at first, but then with Excalibur) to try to set things right which she succeeds in doing for the most part.  When they all return to the past however, one of her teammates in Excalibur, Captain Britain, gets lost in the time stream and no one knows how to find him. His girlfriend, Meggan, is beside herself desparate to get him back somehow but no one knows how.

Although everyone is sad over the apparent loss of their teammate, soon after something wonderful happens. Scott Summers and Jean Grey (this timeline's version of her parents) announce their wedding! Oh joy! Perhaps Rachel can still be born in this timeline after all! She couldn't be more thrilled!

Then something strange starts happening to Rachel. Without warning, her body suddenly takes on characteristics of her lost teammate. The effect is only temporary but has Rachel secretly puzzled. Soon the secret is out and Meggan begs her to try to get him back to our time. She doesn't even know how, but one thing she does know; only one of them can remain in this particular timeline at once, not both. She would have to sacrifice the life that she has made for herself here in order to get him back. Why now?! Why when everything is finally going her way, is she now asked to leave it all behind for the sake of another? This tears her up inside, but she knows what she must do. After all, this place was never supposed to be her home to begin with. And besides, now that her parents were getting married, she could still have a life in this timeline through a child that they would bear named Rachel.

With the assistance of Daytripper who has magical abilities, they find Captain Britain in the time stream, and he and Rachel trade places. In tears, Rachel disappears to who knows where. That seemingly was the end.

But...she eventually finds her way to a future (that no longer exists now) and had a new goal in life...to stop Apocalypse who has made that world a living hell. She forms a quasi-religious cult there and is called Mother Askani.

This cult would later be responsible for saving the life of her (half) brother Cable (Nathan Summers.)

The cult trains him to one day destroy Apocaplypse. As adult, he travels back to the past to do so. Cable however needs guidance during his childhood and Rachel, now elderly since the Phoenix entity left her, gets two bodies with very similar powers to her parents and transfers her parents minds from the past (while they're on their honeymoon! Bad timing Rach!) into these bodies prepared for them so that they can raise Cable as their own child.

This was not revealed to Cable however, until he returned to our present timeline (although he somehow suspected it all along.) Right after the transfer of her parents minds to the future, Rachel "dies" although not quite because she appears to Cable in the form of a teenager and later tells him that she will never leave him. And besides that, how could her parent's minds remain in the future and get sent back to the past later if Rachel isn't somehow still around. I guess her spirit or "essense" remained to watch over them.

Ray is now back in the present thank goodness apparently for good this time.
You can read her return in X-Treme X-Men and then her new adventures in The Uncanny X-Men and the upcoming X-Men: Emperor: Vulcan series