Cultists:
So I have this headcanon that Raphael would absolutely be attempting to corrupt people and turn them into worshippers and/or cultists for his own cult.
All Archdevils (and powerful deities) have their cults, and it's something that ALSO grants them power. After all, to be a god, you need the power of faith in your name and those willing to serve and devote themselves to you and your cause.
We know that Mephistopheles canonly struggles to keep cultists, because they quite often get mixed up with the cult of Asmodeus. This is something that highly frustrates Mephistopheles, because he's actually losing people and influence to a rival (despite Asmodeus being the Archdevil Supreme and ruler of the Nine Hells).
Raphael would likely know this (especially because Mephistopheles is his father, I imagine he's heard his father bitch and moan about Asmodeus once or ten thousand times lol).
What better way to get back at his father than to ALSO try and start making a cult of his own. Of course, Raphael is self obsessed and in love with himself enough to think that he has earned a following, that he is capable of gaining cultists (let's be honest, there's enough Raphael fans in the fandom to start a mini cult so why not think it's possible for him to HAVE cultists in his name in the game?).
These COULD just be warlocks. These COULD be people who were like Gortash that he bought and tried to twist into his perfect little follower (but we know Gort absolutely broke those rules).
This COULD be Korrilla, and could also potentially be Hope. Maybe his infatuation with getting Hope to snap is because if he can't get her to follow and worship him and bend the knee, then others will refuse as well. It's a move against the lanceboard.
My personal hc is that Hope and Korrilla are not just sisters, but twin souls from the Thunder Blessing. To increase birth rates, they split each existing soul in two when it came to gold dwarves. So my little hc is that Raphael is so desperate to get Hope to follow him because hers and Korrilla's souls are ONE (and ofc the more he has the better--but the idea of having that twin soul put back together just feels like something so Raphael). I also feel like they are meant to represent light and dark as a whole.
Raphael seems to spend quite a lot of time on the Material Plane, obviously to make contracts and deals and gain souls, but what if it was also to gain a following. I can't see him passing up the opportunity to out cultist his father. He ALREADY is so convinced that he's going to become a god, it would be likely that he already has some semblance of a following (even is miniscule).
Most desperate mortals, so broken down and needy, it would be simple enough for him to play into their needs and suddenly have someone that has faith in him. He's, of course, put them entirely in that position (by humiliating them, killing off people, making political moves or personal moves against them) so they end up at his feet, but he also calls himself their "saviour". Why wouldn't they believe in him and put their faith in him when Raphael tends to use a corrupted and manipulative tact of "kindness" against them.
We also know Raphael IS of high status due to Helsik saying so when you talk to her after killing him. She's impressed you managed to kill him, and mentions that there's a lot of talk going on in the Hells because of it.
High status also explains why Raphael has so many souls within the HoH. Souls are supposed to be collected and used for Archdevils to power up their realms, not just lesser devils' personal uses. Soul coins are their currency, yes, but Raphael just has like 1,000 souls floating around in his house like it's totally normal (it's not, only devils of high status have slaves in their name and souls they can corrupt and turn into slaves or other devils--OR also use for their magic and other abilities that they use to give them power; this could be running his HoH which seems to run off infernal engine like power or as we see in game, gives Raphael his ascended form but it appears to be limited).
I just think Raphael would totally have cultists he would have spreading word of him around. A devil that aids and helps mortals in need, a devil that is smart and handsome and charming, and you can totally give yourself to him <3 He won't eat your soul or anything >.>