Disclaimer: I don't own Angel. Joss Whedon does.
Enough
Fred had been given clean clothes, a room of her own, and time alone while Cordelia, Wesley, and Gunn tried to comfort Angel. But the vampire wasn't really the sort of person that you comforted. He sort of half-listened, his eyes glazed over with shock and grief, and then quietly told them that he needed some space.
When Cordelia came to check on him the next morning, they found that he had left. There was a note on the door explaining where he had gone, and, though they wondered at his choice of going to a monastery, they all agreed that it would probably be good for him to get away for a little while.
By the time that they got around to checking on the strange girl that they had rescued, she had already scribbled the properties of matter on the wall, and was just starting on the Laws of Motion.
After they had confiscated her marker and she had stopped rambling about one dimensional motion, she asked where Angel was. She got very quiet for a moment after they told her he had left, and then she meekly asked if he would be back soon. When they admitted that no, they weren't certain when he would return, she just stared at them. Then she let out one loud, wailing cry, turned around, and dove behind one of the stuffed chairs and refused to come out.
She only came out once during the first month, and that was only to ask for her marker back.
Her walls were almost completely covered in writing by the end of August. Most of the time she wrote theorems and formulas, but sometimes she would scrawl strange little phrases. She didn't talk much, but when she did, it was in small outbursts that rarely made sense. She'd break off her sentences in the middle, start a new thought, and then stop talking entirely.
They made sure to send up lots of markers and tacos, and mostly just left her alone. But Fred didn't mind. She had Physics, and that was enough for her.