In Avatar!Verse, Tyson is an earthbender living in Ba Sing Se.
Though they have a long history in Ba Sing Se and were largely Earthbenders, the Delaney family claim to fame - outside of the teaching aspect - in this verse was a long history of benders from different elements going back generations before the Hundred Years War.
This verse is primarily set after the events of Avatar: The Legend of Korra, with Tyson’s Great Great Great Granduncle (Jethro) being one of the last of the original Airbenders in hiding and Tyson’s brother being named (Jethro Andrew) in honour of the return of the Airbenders.
The skin around the dent in Tyson’s torso is covered in burn marks from Sebastian’s attacks. He has suffered other minor burns from The Colonel’s assaults, but none so deep. The dent causes his daily pain still, but the burns have damaged the nerves enough to muffle some of the pain received from contact.