Yeah... I've been looking and Jack Frost doesn't really figure as a major character in most stories. He's mentioned in lots or turns up as a peripheral character, but not a major one. As such I'm not sure he quite fits the framework you've laid out with Swash.. He would have been very confused nd uncomfortable with it being summer. Hmm... I'm tempted to keep him in reserve, but currently he's interesting me more than Robin Hood, which is maddening.
I would never dream of giving him loads of powers Loves, you know me better than that. Besides Jack Frost doesn't actually seem to be very powerful from what I can tell. It's Father Winter who gets all the good stuff.