>>6 and
>>3 make pretty good points. I'd take that advice myself.
Yeah, the way I see it, it's mostly a clashing of perspectives. A misunderstanding, the kind that self corroborates and gets worse and worse the longer it's left to its own devices to fester. And it's really poisonous in that soon it will dissolve into the perspectives of the concerned parties and what was once merely speculation and misjudgement will cement itself into "fact" for those involved. That is to say, the longer a conflict of misunderstanding persists, the more the misunderstanding becomes reality. In a sort of paradoxical manner the difference in perspective unites in a mutual dislike or hatred. And you've probably seen that and you're right to want to act on it.
So, yeah, it's been said already I believe but it doesn't hurt to say it again; have them sit down and talk to each other. They need to hear it from you and each other, that they're propagating their own perception of the issue beyond reason due to the circumstances and tunnel vision regarding perspective. Mostly regarding Dylan, though it can apply to Leah too, there needs to be a better effort to not only communicate clearly, in a two-sided manner, but to simply look at the other person's perspective and try to understand better. And the communication would obviously help that happen, and you, as a mediator, have the objective of seeing both sides of the story, as well as having a third-party opinion. So bring them together, with you, exercise your judgement, tell them from an objective perspective what's happening, you know, that it's a misunderstanding, and have them talk to each other and listen to what the other person has to say instead of talking AT one another or talking ABOUT the other person, because that will help to propagate misunderstanding.
Sometimes friends do incredibly stupid things, and you have to remind them, firmly and honestly, that you're there for them and that as their friend they're being stupid ;). Everybody's different, and as their friend you will probably know the best way to approach them, so do what you can to open their eyes and cleanse their vision of misunderstanding. That's my advice; I hope it helps and I hope they manage to regain their middle ground with each other~