Sad thought randomly hit me. Imagine Simon nearly meets the same fate Soap did. For months, he's in the hospital recovering. The only reason he lived is because he was only barely hit.
He heals, but he can’t return to service. He has trouble keeping track of things and his memory starts to go. So, he moves back to Manchester. He gets a dog who grows old with him. He finds some new friends and stays in touch with his friends from the military.
But as he gets older, around 65, his memory continues to worsen no matter how many puzzles or brain activities he does. Part of it is the injury but most of it is the fact he's getting older. It gets to the point where he can no longer remember if he's eaten or showered. Price or Gaz offer to help, but he declines since he knows they aren’t in the best shapes either.
For his own health, he goes into an assisted living apartment. He can do most things on his own, but needs to be reminded of what he has and hasn’t done. One of the staff has an accent exactly like Soap's.
And while the staff member has told him his name multiple times, Simon always calls him John. He knows it isn’t John. But the voice reminds him of him. He constantly asks him, "Are you good at art? My John was good at art."