There isn't much of the archived network available, only about a month's worth of posts. Mello's first appearance occurs in response to an informational broadcast from Chris, who Near will likely recognize from Mello's more recent argument about his proposal on killing Sharon.

A year and a half is a significant amount of time to have spent elsewhere. Mello feels entirely stupid for not having realized it - irrationally so, perhaps, because there is no good reason for Near to have disclosed that to him, and Mello recognizes that. If their circumstances had been switched, he can't say he would have done any differently. Still, a heat of heat irritation crawls up his spine, because he also recognizes that this is just another way in which he is so far behind Near, without hope of ever catching up.

"And one of these places is where you learned magic? How?" There is no doubt in Mello's mind that magic is exactly what he's witnessed. Magic isn't known to exist in their world, outside of the realm of fantasy, but it would be foolish to assume that was true of all realities, especially given the evidence, that Near is clearly capable of performing magic.