>>12098
So from a physical standpoint, try to imagine how it would feel to be in bed 24/7 and what that would do to your joints and muscles. Imagine how it would feel to make simple movements in bed (sitting up, rolling over, lifting a leg, etc.) given this, while also having hundreds of extra pounds on your body.
From an emotional standpoint, even the most committed feedees can get frustrated with their weight or worry about their health somewhat regularly. Being in bed 24/7 can also be quite boring and monotonous, as you can imagine. Whether or not another character(s) offers emotional comfort depends on the type of story you are writing. Remember that unless there's some kind of unique circumstance, even immobile fatasses tend to have friends who come by occasionally to chat or help out.
Oh yeah don't forget these people regularly eat over 10k+ calories per day like it's nothing. Often times, food is one of their only sources of pleasure. (Remember that being immobile tends to boring) The immobile character should be able to casually eat through a family's worth of food for a meal like it's nothing, but also be choosy enough to eat what they prefer.