[@BlackPanther]

First of all, a mistake on my part - they are known as Skinwalkers, not Skin-changers.

Overall, your sheet is just way too vague. For a High-Casual, borderline Advanced Roleplay, I'm going to need a lot more detail from you; I'm not looking for IC posts that are going to be of this standard, so it needs to be more in depth.

Starting from the top: "Old" As an age, doesn't really cut it for me. If it was an ancient creature like an Angel, I could sort of understand, but I'm going to need some sort of estimate. 

Personality; going to need more than one line from you. No-one is that two-dimensional in real life. I mean, you've stated that one of his weaknesses is that he regrets his past, and it is 'debilitating'. Does it cause him depression? Crippling anxiety? Whatever it is, it contradicts the personality traits you've listed.

Backstory; I don't mind backstories being expressed IC'ly, but I still want something written down in the CS other than "it's a long story". If it were going to be relevant to the plot, then yeah, I could understand that you want some mystery in there - but the main plotline is stopping Seals being cracked open. And you've wiped out the mystery by saying what his tragedy is - a dead wife. That to me just looks like you can't be bothered writing out a decent backstory for this character until it becomes relevant in the IC - If you are really stuck on how to write this out, I don't mind waiting for something good, and you can always ask me for tips and the like on what to put.

My final issue is with the Hybrid nature - you haven't said how this has occurred. Now, Vampires are canonically sterile, so it can't be a Skinwalker Daddy/Vampire Mommy. I'm not sure if Skinwalkers can pass along their infection via genetics, but they turn people the same way as Werewolves usually. So, you need to decide which specie he was first when he was infected the second time, or if he was just unlucky enough to be attacked by these creatures on the same night; while still staying alive throughout it - which will also need to be explained, because they generally don't leave people alive.

You haven't mentioned anything of his diet - can he eat and digest human food? Is he still technically alive and functioning?
I can't understand why you've put Iron as a weakness, when it doesn't affect either of the species he belongs to. Does sunlight affect him? Does silver affect him? Does Dead Man's blood affect him? And why is it so damn hard to kill him? There's no way he'd be harder to defeat than a Leviathan, and for them, all you have to do is separate the head from the body and keep it away from said body. All it takes to kill a regular Vampire is beheading them (And fire, I guess?), and for Skinwalkers, it's sustained damage, and/or silver to the heart/head.

So, yeah. Sorry man - this is going to need a lot of tweaking.