At this point, I think it's pretty clear that Micchy has nobody's best interests at heart - possibly not even his own, in the long term.
He wants Mai, but he doesn't really care whether she's happy or not, and he clearly doesn't respect her or even really understand her - he does things she knows she doesn't like to impress her (like becoming a Rider in the first place); will go over her head and use her happiness as a weapon to force Kouta into line, even though he must know that she'd hate that if she knew; and he'll cheerfully escort her and the other members of Team Gaim down to a shelter under false pretenses - but won't tell them so that they can save their families.
He seems to simultaneously want Kouta's friendship while also absolutely hating the fact that Kouta is stronger (physically, mentally and emotionally) than him and can't be controlled. It's almost as if he doesn't want to be friends with Kouta, he just wants to control him and have his affection, which is - more or less what he wants with Mai, as well. His constant attempts to manipulate Kouta, absolute rage at Kouta not falling in line, seems to pretty much be what would happen to Mai if she reciprocated his interest.
Thing is, I feel like you could replace Mai with any charismatic, attractive young woman about his age, and Kouta with any charismatic, attractive young man, and Micchy's behaviour would be exactly the same.
He wants to be able to control Ryouma, Sid and Yoko, too, and he doesn't seem to have realised that he's small fry compared to them. They are much better manipulators than him, and they all know it, and he's the only one who doesn't get that. He wants his brother's respect, but he also wants to be able to work against him behind his back.
And ultimately, he's not thinking in the long term: The impending apocalypse seems to almost be a side issue for him. He's not interested in Yggdrassil's ideals - nothing he does has 'save the world' as its main goal, it's always to advance these manipulative, parasitic relationships he has with people. He's as blinkered and short-sighted as he is treacherous.
... I have a lot of Micchy-related thoughts, okay.