Nova

Personality: Silly and hyperactive. Nova likes getting into trouble with their gang. They're sort of a menace, up to petty crimes, but they never want to actually hurt anyone with their antics. 

Backstory:

Nova lost their arms and purpose in a deep dive gone wrong. 

They were on an ordinary dive down with their team to make repairs on an underwater pipeline when they were attacked by a pod of unidentified sea monsters... Being a mantagrem, Nova was able to manoeuvre themselves out of the beast's jaws, but by the time they realized what was happening their teammates were already being devoured. 

They reached out in an attempt to pull at least one of their friends away from the slaughter, but just then one of the beasts lunged forward and tore Nova's arms right off of their body.

Nova doesn't know how or why they survived, the trauma from losing their friends and arms in such a brutal way has left a mark on their psyche.