Pact Soul

Sorcerers come in all forms, as do the origins of their magic, so Pact Soul sorcerers are already a mixed bag within this mixed bag of a caster. As a Pact Soul sorcerer, an ancestor of yours was a warlock doomed to serving a higher power for all eternity. While you have mostly averted that same fate, that patron’s eldritch touch has reached you, imparting you a taste of that power in the hopes of you serving them.

Patron's Touch

Your link to the powers beyond allows you to learn spells normally associated with the Warlock class. When your Spellcasting feature lets you learn a sorcerer cantrip or a sorcerer spell of 1st level or higher, you can choose the new spell from the warlock spell list or the sorcerer spell list. You must otherwise obey all the restrictions for selecting the spell, and it becomes a sorcerer spell for you. 

In addition, choose a Warlock otherworldly patron for the source of your eldritch power. You learn an additional spell from that Warlock subclass’ extended spell list. It is a sorcerer spell for you, but it doesn't count against your number of sorcerer spells known. If you later replace this spell, you must replace it with a spell from that subclass’ extended spell list.

Sorcerous Invocations

Starting at 1st level, you gain an eldritch invocation of your choice. Whenever you gain a level, you can replace the invocation with another one from the warlock class. If the invocation has a prerequisite, you can choose that invocation only if you meet the prerequisite and you count as a warlock for the purposes of such. You gain another invocation at 3rd, 5th, 7th, 9th, 12th, 15th, and 18th level.

Soul Boons

At 6th level, the magic tied to your birthright manifests itself into boons normally granted by patrons as gifts. You may choose a pact boon from the Warlock class.

Pact Apprentice

At 6th level, you gain your chosen patron's 1st-level benefits. However, you do not gain any bonus cantrips or proficiencies from the patron. If an applicable feature requires a saving throw or calculations involving warlock levels, you use your sorcerer levels and spell save DC

Pact Mage

At 14th level, you gain your chosen patron's 10th-level benefits. If an applicable feature requires a saving throw or calculations involving warlock levels, you use your sorcerer levels and spell save DC.

Pact Archmage

At 18th level, you gain your chosen patron’s 14th-level benefits. If an applicable feature requires a saving throw or calculations involving warlock levels, you use your sorcerer levels and spell save DC.