** spoiler omitted **The basic premise is you are not the person you were before. In the story you were an archaeologist who found the bonded object on a dig, but you can insert whatever background fits your starting skills.
Essentially upon coming in contact with the alien device, it used some kind of a needle prick to inject you with the preserved DNA of some lost race, turning you into a hybrid. Your starting Race doesn't change for the purposes of character build, but the physical changes you're just starting to feel at L1 will come into play when the Aberrant bloodline powers fully manifest.
Your Sorcerer powers and spells, then, are inherent in that new DNA, as if you're part you, part something from the ancient past. This new self, growing inside of you, is bound to the primal forces of magic and time themselves, realizing this bond through spells and abilities. While you can control these to a point, their development and initial manifestation is beyond your reckoning.
This character is transforming, slowly, into something they don't yet understand. You can play this however you want, but for me I'd add a touch of fear to the PC. The Gruesome Shapechanger feat is another expression of this change and not at all something you were expecting.
Because of the conflicting nature of your changing body, your mind tapping into some ancient entity's subconsciousness from an age long past, this helps explain your lowered Will saves from Crossblooded. Your mind is at conflict with itself and constantly dreaming of some ancient city which, of course, will become your Greater Mindscape someday.
I love this, thank you