It Chapter 2: Every Character Ranked Worst To Best
8. Mike Hanlon - Isaiah Mustafa/Chosen Jacobs
With Ben no longer in charge of passing on the history of Derry, that honour falls to Mike (played by former Old Spice commercial model Isaiah Mustafa - a fact I mention because it will keep popping into your head every few minutes in the movie). He never left Derry, so he's not subject to the same memory issues as the other Losers.
Sadly, Mike is where the film should have deviated from the book. He's not a direct retelling of the novel's version of Mike, but the Ritual Of Chud that forms the end of the 1958 sequence is reused so Mike becomes the one who takes charge of it. It didn't really need to be used at all, since it fails and since It isn't defeated the same way as in the book.
He's an okay character, but there's so much of the usual King nonsense in his character's arc - because he sought out the reason behind It - that he's asked to complete an almost impossible task. We get a lot of him talking about his quest to uncover the ritual and the need to do it, but there's not much development in there at all.
It's not wrong that he discovers the ritual, by any means, it's just that it ends up being a replacement for his personality somewhat. That goes for his younger self too, because he's mostly just left out other than as an ensemble player.