Cristina is a recurring character in and one of Lincolns schoolmates.
Cristina seems to be an acquaintance of Lincoln and goes to the same school as him. There hasn't been any vocal interaction between them, and she has not had any speaking roles yet. Lincoln had, and probably still has a crush on her.
She first appears in Making The Case When Lincoln wanted to apologize to his sisters for posting his video of them displaying their most embarrassing secrets and moments by making an even more embarrassing video about himself, one of the things he did was put a photo of Cristina over one of Lucys dolls and pretend that they were a couple, speaking romantically and attempting to kiss it. When Cristina saw this, she was rather uncomfortable about it and, as Lincoln explains, switched classes presumably to avoid making any further contact with him. It is unknown if Lincoln still likes her after that.
In "For Bros About To Rock", she makes a cameo at the beginning of the episode fawning over the picture of the polar bear alongside her classmates.
Cristina later makes a cameo in , where notices her and thinks she's perfect for Lincoln, likely unaware that she saw her in Lincoln's embarrassing video in . Lincoln doesn't make any comment about it and Cristina just disappears from the scene later