probably not.

Cause dragons benefits the death of the other?

That, and depending on who kills him, it may end up establishing a better position for master. Especially if it's me XD

Ehh.. It's hard to really say.

From what I gather on one side of the coin: Juke does genuinely love and care for Keino. But on the other side he kinda goes about it... wrong I guess? I dunno the full story but the dude did brainwash him and all that.
But he might have his reasons. Maybe Fate dealt him a bad hand in his past.

I am curious to see if he can get saved and what the aftermath will be if he is saved or not.

You're correct there. I going to say that in the past (In the comic) Juke was a gentle soul dragon when he met Keino and took him in after he saved him from near death.

He trained the pup in hopes for the future, but during the times when he has feelings for Keino, like most masters do with their students, but in Juke's case, Keino reminded him of someone in his past he lost, which is why he was falling for the pup, but it was a bad thing cause his strong resilient mind was weaken which something was over taking the dragon, leading him to do terrible things and soon mind control Keino.

Can't much say for now till we get to that part of the story, don't want to spoil for everyone. x3

And yes, it will be a choice the anti-hero makes, and the aftermath of this battle.

Since he's a villain type, most people probably wouldn't be sad. But of course it's always a bit sad to lose a character you are used to over time.

He's here till the story reaches that part of the story, when everyone would root for the end of the bad guys to lose, but soon will see the back ground stories before the defeat or death of the baddies.

The end leads sadness and sorrows.

Unfortunately it's mostly like that with the evil guys, many are evil for a reason. It certainly will be interesting to see this backstory.