When designing characters like this as single cards you should always consider which characteristics to portray and the specific way you do it, especially if you design them as the part of a set.
For example most creatures of the Nightwatch, if put into MtG as a faction, would indeed be Rouges, so it would actually make sense for Jon Snow to buff them up, portraying his leadership within the Nightwatch, even though he himself is not that much of a Rogue.
But I really don't understand the choices you made for his abilities. First Strike does a good job here (after all, it is usually used to portray a creatures supreme agility and overall dexterity in combat, which is just about Jon Snows thing in general), but I neither get the Hexproof, nor the buff for Berserkers. Berserkers seem to be more a type for the wildlings, among which Jon Snow does not really fell that comfortable. It also just breaks too strong with the flavor and color alignment. Hexproof is a green or blue mechanic, while the colors you could assign a berserke too are black and red; It doesn't suit Jon Snow. Why doesn't he give other Rogues +1/+1, or maybe he shares his First Strike with them, maybe even both?
Ygritte's portrayal is kind of blunt. Sure she is the one starting to hook up with Jon Snow, but does that really allow for gaining control of ANY target Rogue? it's not like dating brothers of the Nightwatch is her hobby or something. Rather than that you could give her something like a "fights target creature"-ability etc Also Berserker is just not that much of a fitting creature type and with 2/1 she is by far too weak for her current cost.