Star Paladin Cross is the 3rd highest ranking Brotherhood of Steel member in the Citadel, but no longer works in the field. Instead, she now serves as Elder Lyons's trusted bodyguard and advisor. It is well known that Star Paladin Cross has been technologically enhanced so that she no longer needs to eat or sleep, due to the fact she is a cyborg. This occurred several years ago, after Cross was critically injured defending Elder Lyons while out in the field; Scribe Rothchild performed the enhancement operation that saved Cross's life. Cross is also the Brotherhood of Steel soldier who helped save the Lone Wanderer's life as a baby, serving as a guard at Project Purity prior to the birth. Cross helped James, the father of Lone Wanderer, get through the super mutants and escorted them all the way to Megaton.
Because she belongs to the Brotherhood of Steel faction, Star Paladin Cross instantly becomes hostile towards any nearby Brotherhood Outcasts if she is dismissed from the party in their presence. This can be exploited for farming Outcast weaponry and armor without a Karma loss, as at high levels she is able to wipe out entire groups of Outcasts.
If the player destroys the Citadel during the Broken Steel quest Who Dares Wins while Cross is a companion, she will become hostile along with the rest of the Brotherhood of Steel.
Star Paladin Cross can be recruited as a follower if you have Good Karma.
If you insult her or your father, she refuses to follow you.
With the Broken Steel add-on installed, you will be able to ask her to join you once again after completing Take it Back!, even if you previously insulted James (but the positive Karma check still applies).
pcps3xbox360 Sometimes, if Cross dies in battle, you will receive a message many in-game weeks later, stating that "Star Paladin Cross has returned to the Citadel." [verified]
pcps3xbox360 If you tell Cross to wait, then reopen dialogue with her later, she will act as if you hadn't told her to wait and have normal dialogue, but she will still remain in that spot indefinitely. Firing her and rehiring her can fix this, but remember that you must have good Karma to rehire her. [verified]
xbox360pc If you make Cross hostile towards you (after she has been made a companion) she will not have a unique line when spoken to, but instead talk as if she is still a follower. If you tell her to switch to a new weapon, she will attack you with it upon exiting the conversation. [verified]
pcps3 If you give Star Paladin Cross items to carry for you, she will fail to move. The only way to get her to move again is to take the items back, dismiss her, and then ask her to again become your follower again. On the PS3, this can happen when she is asked to wait; the solution is the same, but the problem will reoccur whenever she is asked to wait. [verified]
xbox360 Sometimes while entering areas such as Vault 87 Paladin Cross's hands will grow to humongous lengths, similar to that of a Deathclaw, yet she can still use her weapons, waiting or entering and leaving an area seems to fix this. [verified]
xbox360pc Sometimes, if you kill Dogmeat whilst having a companion (usually Fawkes), and hire Star Paladin Cross, through a series of actions she may cause the whole town of Megaton to randomly become hostile to you. First, you have to take her there. Bring her into My Megaton House, and tell her to wait. If the glitch where she acts like she was never waiting but waits anyway occurs and Dogmeat's puppy isn't waiting at Vault 101 (or you don't fire Fawkes) you can still fire and re-hire her. Taking her outside, however, causes the entire town to be hostile. Be wary of this, because if you don't have a recent save prior to re-hiring her you may have to retrace a lot of ground, or simply kill all of Megaton. [verified]