Does such a feat or trait exist?

[Andre Roy]

I've been searching around and I can't seem to find what I'm looking for and was hoping others could help me.

Basically is there a Feat/Trait/Archetype that allows an Arcane Caster (more specifically a Sorcerer) to have access to Divine Spell or one Domain?

Or, invertly, is there a Feat/Trait/Archetype that allows an Divine Caster (more specifically a Cleric or Inquisitor...maybe a druid) to have access to Arcane Spell or a Bloodline?

I've got this concept in mind that to work best I would need to have access to the Full Serpentine Bloodline and the Scalykind (or druidic Serpent) Domain

[CalethosVB]

The Variant Multiclass system from Pathfinder Unchained might work for you. You can pick up a Domain or some Bloodline Powers.

[Andre Roy]

Oh right, I haven't thought of this. If I go base sorcerer and take cleric as a side, do I also gain Divine spells or just the Domain power?

And if I go Cleric/Inquisitor as base and take Sorcerer as a side, do I get the Capstone power?

[0o0o0 O 0o0o0]

Sorcerer just gets the Domain (and channeling) with VMC so you get the animal companion but not the spells.

Cleric can't get the capstone with VMC sadly.

The Scalykind spells are okay, but not as good as the Serpentine ones. You will miss Magic Fang, but you can pay for that to be Permanencied. You could consider Druid VMC. You get the animal companion, and it is at Character level at 11. You also get the Wild Shape stuffand shape change. The thing you want from the Scalykind Domain is the snake Animal Companion, but you only get that at level 15 and you still need to spend a feat on Boon Companion to make it good. VMC Druid does that at 11 plus other nice stuff.

For my snake lord I would do Nagaji Serpentine Sorcerer VMC Druid. You are a shapechanging magic snake.

The problem with the Domain is that Venomous Stare is the only power you will get for a long time, it isn't great and it is Wisdom based, your guy is a Sorcerer who will have bad Wisdom. Serpentine Sorcerers can get poison anyway and Nagaji can spend a feat on spitting venom. And they can get a gaze attack anyway. I wouldn't do that, because it loses your bonus to Handle Animal with snakes, but it is there.

[Dark Immortal]

Eldritch Heritage will give you access to a bloodline power, also there are other feats in that tree that provide access to further bloodline powers.

There are a few traits which can help you, as well. Magical Talent provides you access to any 0 level spell from any spell list as a spell like ability once per day. Technic Tinkerer works very similarly.
Two-World Magic will function a little differently by adding any 0 level spell not on your class list, to your class list. If you are of genie blood there is minor wishcraft which is an interesting way to go about this, Greenblooded is a limited trait but provides a druids orison as an SLA, Infernal Bastard for a Tiefling in a home game is a potentially useful trade (you lose limited use Darkness for unlimited use 0 level spell). I thought there was another one, magaambyian arcanist, but I cannot find it. This list, however, should be sufficient.

[Andre Roy]

Well if I were to go VMC Cleric I'd probably take the Venom Subdomain, but it's still somewhat weak as it is based on my Cleric level and Wisdom.

The Druid Serpent Domain is much better though, but need to be a druid to have access to it.

Eldritch Heritage (and the Improved and Greater version) could be a good option with druid as a Base (as the Wild Shape and Serpent Domain) emulate the Sorcerer Capstone power quite well and earlier.

The idea is a Human with the Reptilian Heritage (Serpentfolk) Alternate Racial Trait (Horror Adventure)and the Serpentine (or Envenomed) Bloodline and the Scalykind (or Venom) (sub)Domain...to king of make him a Cultist of Yig.

But switching it around as a Druid with Eldritch heritage and it could work too.