|Mileage may vary.|
Unless, that is, you decide to give them to a more martially-inclined class.
The eldritch heritage feats (eldritch heritage, improved eldritch heritage, and greater eldritch heritage, on pages 149 and 152 of Ultimate Magic respectively) allow any character, regardless of class to gain bloodline powers. If you take all three feats (which will require playing till at least 17th level), then you can gain up to the 15th level powers from any single bloodline.
|So what good does that do me?|
So you get a minor feature of the sorcerer class, big deal, right? Well, as with any other mechanical trick you need to look at all your options in order to come up with a long-term goal that will make your character more effective.
For example, let's say you wanted to utilize the most basic power of the serpentine bloodline (Advanced Player's Guide 139). This power gives you fangs that you can use as a natural weapon to deal 1d4 points of damage, and to deliver a poison which does constitution damage, and whose save is equal to 10 + 1/2 your sorcerer level + your constitution modifier. The fangs are eventually considered magical for overcoming DR, and your poison grows more potent the more levels you gain. This kind of ability isn't that big of a deal for a sorcerer, but what if you gave that ability to a barbarian with the brutal pugilist archetype, who also had abilities like Raging Grapple? Perhaps a wrestler from Sargava whose ropy muscles are ideal for wrapping around enemies before sinking his fangs into their necks, quickly draining their constitutions and leaving them unable to continue the fight?
There are dozens of combinations of class and powers you can create to boost your mechanical performance, as well as adding intriguing elements to your character's backstory. For example, a Kellid fighter with an eldritch heritage from the nanite bloodline (Pathfinder Player Companion: People of The River) gains powerful bonuses from the nanotechnology living inside of him, but did that same heritage get him cast out from his tribe for bearing the mark of the machines? A druid with the verdant bloodline gains a useful ability to disarm or trip enemies using a 15-foot vine, bonuses against sleep and poison, along with being treated as if they're wearing a ring of sustenance, which would give the character an otherworldliness as she snacks on fresh air and sunlight. A philosophical assassin who comes from the starsoul bloodline would be able to use gas weapons without risking harm to himself, or he could exist in a void such as the space inside a bag of holding without problem (which would allow companions, or even bestial familiars, to carry the assassin past human guards to infiltrate a target's home base).
Cautions and Costs
Nothing comes for free, and the eldritch heritage feats are no exception. They require you to take skill focus in the skill associated with a bloodline, and they have a steadily increasing charisma requirement that can be problematic for some class combinations. So you need to keep in mind that the bigger the power you want from the bloodline, the higher your charisma will have to be, and the more feat slots you'll need to take up.
|All right, let's break this down...|
Put another way, if you want to get the most bang for your buck out of these feats you should look for low-power ones that will naturally grow with your character level (the serpentine bloodline's poison is a perfect example of a power you get with one feat, but which keeps growing as your character level advances), or to combine them with classes that get other benefits from having a high charisma.
For example, a paladin with infernal heritage is both intriguing as hell (so to speak), and it provides a nice dovetail. Paladins gain a huge number of benefits from having a high charisma, and the infernal heritage provides the paladin with a debuff touch attack, poison and fire resistance, and if you make it all the way to 17th level, you can gain the ability to call down hellfire or to grow devil wings and fly. So if you're going to be using your charisma (swashbucklers, Mysterious Stranger gunslingers, oracles, bards, and any other dashing character classes... including sorcerers who want more bloodline powers), then you're already on the right path.
Half-elves are also a swanky choice, as you get that free skill focus feat out of the deal.
These feats won't be ideal for all classes/builds, and they won't be ideal for every campaign. For example, you might take rakshasa heritage to increase your bluff, but if most of your game is spent slogging through zombie fights then you aren't going to find that silver tongue very useful. If you take a fire heritage, but find yourself fighting demons at the Worldwound, then you're going to have an impossible time making those powers punch through your opponent's resistances.
Now that you've had your warnings, go forth, and create terrible combinations where your character's parents are more than just a convenient reason to adventure in the name of revenge!
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