Huh?

Selina "Dad!?" she exclaims upon seeing Reima suddenly appear here.

He smiles at her and grabs one of Diablo's horns to prevent the demon from moving, afterwards wrenching its head backwards to stop its attack from killing Barnock.

The beam of red lightning and fire is redirected at the roof where the stone above them quickly starts melting into lava, fortunately, no one is under it as it drips down to the floor below.

Diablo "Raaghh! What is this!?" he roars, as one of his horns is gripped in what felt like an unstoppable force.

Reima "Yo, you mind being quiet for a sec?" he asks as if he weren't restraining evil incarnate.

Diablo "I WILL DEVOUR YOUR SOU-" he's cut off as Reima shushes him, the act preventing the demon from making anymore sound without his permission.

Selina "Dad why did you stop me!? I'm going to avenge Tyrael!" she exclaims, trying to pry her arm out of Reima's grasp.

Reima grins, "Hi I'mgoingtoavengetyrael, I'm dad... That didn't really work did it?" he mutters to himself after the failed dad-joke.

Selina "Why are you telling jokes! Look what he did yo Quennie!" she shouts, looking over to where her sister currently was, becoming surprised when she spots Quelaag and Ciri attending to her.

Reima chuckles when he receives a glare from his daughter, "What? You didn't expect us not to keep an eye on you?"

...

Selina doesn't have a response for him, she'd like to be stubborn and tell her dad to shove off, but the relief she experienced when he appeared here overturned whatever need she had.

Diablo had apparently had enough of these shenanigans and whips its tail at the stranger, while Barnock had severed the tip of it earlier in the fight it still retained some sharp bones on the ridge of it.

Reima just shakes his head at the demons attempt at harming him, using Selina's arm which is gripping El'druin to completely sever the tail from Diablo's body. Molten blood spurts out from the wound while they give a silent roar in pain and anger. They try to thrash around to at least deal a small amount of damage to their captor, but everything is easily shrugged off.

Selina "Just end it dad!" she says, anger from what the creature had done to her friends and sister remaining intense in her mind.

Reima "Well, we can't do that can we?" he says matter-of-factly.

Selina "Why!?"

Reima "Why? Because you want to save as many people as possible right?" he questions.

She nods but looks confused, "That doesn't mean we should keep Diablo alive!" she adds, feeling as if her father was trying to teach her a life-lesson.

Reima smirks, "No I'm not trying to pull a fast one on you by twisting your intentions... You really should be paying more attention to what's happening around you though." he says causing Selina to start looking around suspiciously. "Not around us now, I meant in the past. Remember that Diablo is currently possessing a girl named Leah's body?"

Selina's eyes widen at this, having completely forgotten about any mention of that. She shuddered slightly at the thought that she'd almost just killed Diablo, as well as Leah. "You will save her, right dad?" she asks, not even considering that Reima might not be able to solve the problem.

Reima nods, "Of course, I'd never let one of your friends get hurt." he says, letting go of her arm and patting her head.

She frowns at him, "Wait, what about Tyrael!? If you were watching then that means you let him die!"

Reima shrugs, "He's at home having a cuppa with Asgore."

...

Selina "But.. I saw-"

Reima "Yeah, you saw a puppet I'd replaced with Tyrael while time was stopped." he explains.

While Selina is recalling what'd happened and if she could have noticed anything, Mathias limps up to them, his eyes constantly shifting from the duo and Diablo in-case the demon was able to escape.

Mathias "So... You can save Leah?" he asks hopefully.

Reima nods, "I can, though, how long it will take for her to recover being melded with the seven deadly sins or whatever they're called is another matter entirely." he looks down at the still struggling Diablo, "Can you just stay still while I do this?" he mutters in exasperation, giving a light chop on the back of its head which causes it to drop like a puppet with its strings cut.

Reima "Sorry love but I'll need some space to do this." he says, levitating Selina next to Mathias as he walks up to the demon's body... They were still conscious as his chop hadn't actually knocked them out, no, instead it'd merely shattered all the bones in its body.

He strolls up and climbs onto its chest, taking note of the heat coming off of its body that reminded him of his less controlled aura many years ago. His hand is enveloped in a black and red mist that seems to be attracted to his downed foe, the substance trying to escape his control and devour Diablo.

Raising his hand up, he brings it down and plunges it deep into the demon's chest, he continues pushing, coming up to his wrist, elbow, and eventually his shoulder before he nears his goal. Truly this creature was a phenomenon, there were 8 souls present in its body, 3 of which were much stronger than all the others.

They were so powerful in fact that he could tell their identities merely by the aura they gave off, from what he'd heard about that worlds demons, each ruled a specific "evil" and became the embodiment of it. So, for example, if a demon was the embodiment of pain it wouldn't mean they'd be in constant agony... No, instead their body would be designed to inflict as much of it as possible, the singular goal of its entire being to achieve that one thing.