Family members can provide practical help. For example, they can help with making doctor's appointments or taking care of daily chores. Emotionally, they should be positive and reassuring, telling the person that they will get through this together.
Yes, there might be. The Naruto and Attack on Titan fandoms are both huge, and fans often like to cross over their favorite characters in fanfiction. So it's quite possible to find Eren - from Attack on Titan - in Naruto fanfiction. However, it may not be as common as fanfictions within each respective universe.