I like the name Dasher, but it sounds like a reindeer, a videogame mechanic, or a videogame character who's really good with guns and can do crazy jumps over cliffs.
He'd be the main character or the main character's best friend or the main character's arch nemesis. He's someone important, basically.
I wouldn't make assumptions about him because of his name, but I would wonder if his parents were a fan of
Rudolph the
Red Nosed Reindeer, or if they were just trying to be hip or unique.
Cool nicknames would be Dash, Dashy, Daz or Dazzy.
It sounds very masculine to me. I would think that a Dasher was a boy.
https://www.behindthename.com/polls/356294https://www.behindthename.com/polls/356351https://www.behindthename.com/polls/member/181370