mukuro: an ally or enemy?

Sometimes it can be hard to say. For one thing, I personally don't see him as the best ally, especially because his true motive continues even into the future arc. He still wants to take over Tsuna's body and cause havoc among the mafia, which can be understandable. The only real reason why Mukuro is so against being part of the mafia is what happened to him as a child. Even though he's the only one fit to be the Mist Guardian, he only does it for the safety of his comrades, Ken and Chikusa -- otherwise I can't really imagine him doing this big favor for the mafia.

But let me digress for a minute. The Future arc still doesn't clearly define his association with the Vongola, but he definitely collaborates with them (on a certain level) against the enemy. The Varia arc and Mist Guardian deal is only the beginning of this ironic (because Mukuro hates the mafia in general), awkward Vongola-Mukuro relationship. While he doesn't admit to being part of them, it's proven that he went against Byakuran in collaboration with the Vongola family. Though by himself, the Vongola family members he contacted were to follow his instruction to attack the Millefiore family. He infiltrates their base in hopes of gathering information, though not clearly stating his intentions, Byakuran states it for us. In the end, TYL!Mukuro (TYL, ten years later) risked himself in pursuit of valuable information on the enemy and ends up losing his life for it -- there was no way for him to escape the impenetrable walls of Byakuran's room. With whatever's left of Mukuro's power, he relays a message (in the form of a wordless dream) to Chrome and Tsuna of the coming threat.

This may be edited out of the shrine later (at present, KHR is at chapter 192) -- but a possible theory I have on why he risked himself for information. Is it possible that TYL!Chikusa/Ken have actually been slaughtered in this era? While Mukuro adamantly goes on about "not being part of the Vongola", in reality, he is. He certainly doesn't act friendly or buddy-buddy towards them, but those traits aren't needed to be associated with them. All members of the family in the Future arc are targeted - and the people associated with the members directly. For example, like Haru and Kyoko. I think that's the only logical explanation I can come up with (for the time being) to clarify why Mukuro is doing that much for the Vongola in the future. Revenge for cruelty isn't anything new to Mukuro's persona, anyway.

And one more theory to pull out there: "The mafia is in a world-shaking mess, so to save it and purify it myself, I have to use the Vongola guardians. The end." No, he doesn't actually say it but that's just a thought.

Still an enemy? Perhaps. A possible one to be (again). Sawada Tsunayoshi remains to be a "target" and becoming the Mist Guardian only makes it easier and convenient for Mukuro to take over Tsuna's body. This is always Mukuro's reason why he works with the Vongola, and his inner intention is to protect Ken and Chikusa from being captured and executed by Vendicare and the mafia law.