I think of my sorcerers as those who have magic in their background or bloodline, but more ancestrally instead of some other soul trapped inside.
The same here. I like the concept of celestial, dragon, demon, devil or fey ancestry providing innate magical ability- it fits with a lot of stories, myths and legends. However, I strongly dislike the Dragon Heritage Sorcerer with its manifesting dragon abilities. I don't mind it as an option, but I do not want it hard coded as the class feature. I also dislike the heritage giving armor and weapon proficiencies above the basic sorcerer. How does simply having a dragon heritage that provides innate arcane ability provide training in armor and weapon?
I don't see warlocks as seeking out dark secrets to summon evil creatures for the purpose of making pacts. I see them more as the weak or infirm in movies who make deals with the devil in exchange for a promising outcome.
Warlocks are the ones who ACCEPT deals but I don't see them as the ones seeking them out. Instead I see them as the bearers of curses that were brought on by their acceptance of terms from a dark creature. For this reason I expect to see them have powers, but once again I see those powers differently than from a wizard or sorcerer. Where a wizard studies, and a sorcerer explodes with raw power - the warlock is more about having powers that are unseen. They get wings, or improved strength, perhaps (in 3e terms) a few spell-like abilities. As slowly but surely the warlock starts losing their soul and what makes them them and turning into an outsider, elemental, fey or whatever species they made the pact with. In exchange for a boon, and for a favourable result to start (maybe akin to a wish?) they sacrifice their soul and join the creatures they made a deal with.
Long and ramble-y I know, but this article bugged me and I figured there was no way to explain how without giving my mindset. YMMV of course.
I agree about the weak and infirm. However, I also think both those with ambition/power and looking for a quick and easy way to get what they want, or someone desperate (which could include the weak and infirm) also make pacts and would seek out the entity. Examples, would include:
1. The politician in the "Devil's Platform" episode of Kolchak the Night Stalker (the original series from the 70's). He makes a deal with Satan in which he gains a meteoric rise as a politician. He also gains the ability to shape change into a large Rottweiler, a form he uses to kill rivals and others attempting to interfere with his political career. Sometimes, he shapeshifted in front of the person to be killed. Other times, he approached in the dog form or left the scene as a dog.
2. Boris Balkan, the book collector in the Johnny Depp movie "Ninth Gate" takes the book and reads passages hoping to gain power from Satan.
3. Several character's in 70's occult based movies make deals for things like success as actors.
4. People in TV shows like Supernatural and Charmed make pacts. Sometimes gaining mystical ability in exchange. For example, in Supernatural, John Winchester sought out the Yellow Eyed Demon to make a pact that saved Dean. Teenagers in Supernatural , after capturing Sam, summoned a demon to make a pact in exchange for him. There are also the housewives of a book club that make a deal with a demon for good fortune (the demon approaches them, but was possessing the body of another member)
5. The movie the Craft. Girls become witches by making pacts with beings associated with the four elements. One is badly scarred, but none are infirm. One is closer to a sorcerer in that she comes from a line of witches and has natural affinity
Interestingly, none of the above characters get deformed from their pacts. Although, Kolchak succeeding to take the talisman off the politician, who was in dog form, permanently, transforms the politician into a normal Rottweiller. This is why I would not want to see transformation built into the class as a feature.