The option to become a vampire has been a part of the Elder Scrolls games since Daggerfall, but Skyrim's Dawnguard expansion was focused on the sun-dodgers—letting you become either a shapeshifting Vampire Lord, or a crossbow-wielding vampire hunter. What you may not realize is that add-on also defanged vampires to a degree.
Dawnguard reduced the damage caused by a couple of varieties of vampires, disabled a perk that let boss-level vamps ignore a percentage of armor while wielding maces, and changed the frost resistance and fire weakness stats of all vampires. What's more, the effect of hitting stage four of vampirism, where you're supposed to be "hated and feared," was reduced. NPCs will no longer attack a stage four vampire on sight—only one who is in their Vampire Lord form, or feeding.
The Bloodhunt – Cut Vampire Content Restoration mod by ssocialanxiety undoes some of these changes, while also enabling a couple of unused vampiric abilities that were found in Dawnguard's files: Vampiric Strength gives bloodsuckers a boost to unarmed damage, while Dread Cloak gives stage-three vampires a damaging aura once per day.
What's more, Bloodhunt makes the vampiric weakness to sunlight a little more sensible. If you've ever found yourself sizzling before sunrise, you'll know that Skyrim treats 5am as dawn even though it's still dark. Bloodhunt shifts the hours when the daystar burns back an hour, meaning you'll have until 6am to get out of the light, and need to wait until 8pm to come out and play. It also tweaks Vampiric Drain to increase its effect, and fixes a bug that made Drain Life less damaging if you had every fangbanger's favorite follower Serana as a companion.
As a bonus, Bloodhunt gives NPC vampires back their old clothes, which were based on the regular outfits characters wear, rather than the uniform vampire armor and vampire robes that were apparently mailed to everyone in the province who caught sanguinare vampiris. Even if you're not planning to be a dracula next time you play Skyrim, it's a decent addition.
Bloodhunt isn't a drastic overhaul like some of Skyrim's other vampirism mods, but it's a solid example of the kind of "vanilla plus" mod that can improve a playthrough without making it feel like you're not even playing Skyrim any more. It's only available for Skyrim Special Edition, though there is an Oldrim mod that reactivates Vampiric Strength and Dread Cloak. Here are some more of the best Skyrim mods, and the best Skyrim Special Edition mods.