Atomblast was a former soldier for the Battle Of Hybrids, being on the R.E.D. team. He turned against Hybrido in Frostec, motivated to join Frostec and Harmheat against the threat Hybrido posed to humanity.
He died while saving Jono Marwe from Ethan Strange, tied between the two universal diamonds when Ethan created the time portal, instead accidentally causing Atomblast to fall in while pushing Jono out of the way. Jono was horribly abusive and mean to Atomblast, but deep inside, she loved him and didn't want to hurt him, but was forced due to her dark past. Atomblast saved her even though she was hateful to him. That teaches a lesson. Now, Jono was actually hateful to him for a reason. It helped him live longer. Without knowing she really loved him, he would have shot himself, thinking nobody cared about him. Jono was worth saving. So he did it.