This character could have been a survivor from an illithid colony, a failed ceremorphosis candidate, got too close to the Far Realm, read a tome she should not have (if you want to tap H.P. Lovecraft), or was otherwise exposed to some aberrant force. Perhaps her psionic talents attracted the attention of an otherworldly entity, or perhaps psionics were part of the package deal.
At any rate, you start with a hybrid psion/warlock, with the telepathy focus and star pact respectively. The theme is kind of iffy; if you have a background for what your character was all about before this went down, you could go with that (like guttersnipe or outlaw if you nabbed the book-that-should-not-have-been-opened), though seer is good if you want to focus on the whole fate aspect.
Powers are pretty easy to juggle, you will just want to make sure that your Intelligence and Charisma are both set to 16. The telepathy focus works out well, as it is linked to Charisma. I think the only real flaw here is that some star-pact spells are dependent on Constitution, which might be a problem if your DM won't let you just pen in "charisma" over the power description.
You will probably want to dump your first feat on Hybrid Talent so you can pick up something extra. After that just nab a rod or orb and you are good to go, though if your DM is cool with it you might want to ask about re-skinning a few more things:
- Tentacle Lash: I like the idea of a servant (or slave?) of the stars being mutated by her "gifts". The tentacle might always be present, or extend from her hand or even mouth. You could even go so far as to have the character have an entire face of tentacles, complete with a lamprey-like mouth or beak ala the mind flayer. This is just a re-skinned basic melee attack, or even eldritch strike. I would have it otherwise function as a short- or longsword.
- Maddening Drone: More of a warlock power, you have lots of little mouths that whisper secrets and prophecies. This would just deal psychic damage within a close burst. Might not be "balanced", but is thematic and cool. Could have a push effect. If you went with this as a daily I could see it dazing or even stunning.
- Mind Blast: You could simply reskin thunderwave to deal psychic damage and swap out of the push effect for something like a defense or attack penalty, or prevent targets from making opportunity attacks for a turn. Alternatively, save kickers for the augmented versions, up to and including a one-turn daze effect.
- Thought Shackles: The dominated condition does not start until 5th level, and even then it is for one turn. Still you could deal psychic damage, then have the target make a melee basic attack. Or you could have it so that you can make the target use one until they shake the effect off with a save. Like, they get to take their turn, but on your turn you can take control briefly. Something that seems quasi-mind flayery.
I guess the only bad part about this character is that it is seemingly more suited to a villain, though you could go the route of a kind of grim-dark hero. Depending on the complexity of the star's machinations, the character's actions could coincide with the rest of the party. Hell, one star might have the character move against the other one.