Here is a more advanced draft of the Tattooed Archetype - any thought welcomed ;-)
Your innate magic-wielding ability seems to come from the web of magic symbols that were inscribed on your body. You are attuned to one peculiar school of magic (except divination).
On Golarion there is a tradition among the Varisian people to inscribe the mysterious glyphs from the Thassilonian times on their body. Some varisian bloodlines inscribe secret runes among the ritual tattoos and are blessed with more innate magic-wielders than other people.
Level 1 : Rune Calligrapher
You can apply proficiency bonus to any ability check linked to runes or symbols (like analyzing, deciphering, inscribing). If you’re already proficient, your bonus is doubled.
Tool proficiency : Tattoo kit
Level 1 : Tattooed Skin
Natural AC = 13+Dex modifier
You regain 1 hit point when you cast a spell (1st level and higher) from your school of affinity
Level 6 : Font of Power
You will regain sorcery points you spent on spells from your school of affinity after a short rest.
Level 14 : Skinbook
You can store spells on your skin for an ulterior release. This process takes 1 hour and spends 1 sorcery point per spell slot. The appropriate spell need to be cast and additional sorcery points may be spent on metamagic effects.
You can later release those spells as an action (or bonus action if you used quickened spell).
You need to release all spells before you can inscribe new ones on your skin.
Level 18 : Absorb Power
When you are the only target of a spell or effect from your school of affinity, as a reaction you can absorb this spell as individual runes on your skin. This effect will grant you 1 sorcery point per spell level.
You can only perform this if your sorcery point total do not exceed your sorcery point maximum.