A long-time depression sufferer

[Bassim]

Have I made any mistakes?

A long time depression sufferer, Tom wore a perpetual frown. When some of his friends cracked a joke to brighten him up, the frown would vanish for a second and then return again. For those who didn't know him well, Tom was probably viewed as a spot-spoiler, but for his friends he was a warrior, fighting depression with all his might.

 

[abaka]

A long time sufferer of depression, Tom wore a perpetual frown. When some of his friends cracked a joke to brighten him up, the frown would vanish for a moment and then return again. For those who didn't know him well, Tom was probably a spoil-sport, but for his friends he was a warrior, fighting depression with all his might.

You may consider saying "Long afflicted with depression,..."

PS. Also consider saying "To those who didn't know him well" ("casual acquaintances"?) and "to his friends".