Thomas Riker during/after the Dominion War

[dupersuper]

I feel that

Spoiler

the last episode of Lower Decks, wherein the topic of transporter clones was raised,

if Thomas Riker were still alive, we would know.

I feel the opposite: Riker didn't seem sad or wistful or anything.

 

[Unimatrix Q]

I remember a cover from a Star Trek comic (that i never read) with Thomas Riker apparently experimented on by the Cardassians (apparently it had something to do with the transporter malfunction that split Riker in Will and Thomas)

Has someone more information about it?