How about two archetypes for DnD 5e on a theme-what is you get powers from a creature who is not a patron? Here is one for a druid and here is one for a Sorcerer
Circle of the Dead Guardian
While in nature, a soul bound to the woods took you for its ward. You were not a druid when you entered in the woods, but due to this creature of bone, shadow, and death love, care, or choice, you are now granted the powers of the woods and necromancy. You may not want this, but you are now given this. What will you with your new power over life?
Starting at second level, you gain an undead companion. This creature must by of CR 1/2 or lower and undead. You and your companion share a connection so you may give the creature mental commands, even when unconscious. These commands are limited in scope but as an action you can command the beast to take the Attack, Dash, Disengage, Dodge, or Help actions.
If you undead falls in combat, you may seek it out again by spending eight uninterrupted hours alone in nature.
Power of unlife
Starting at level six, you gain all wizard necromancy spells as part of the divine spells you can prepare.
Starting at level 10, when you use your wild shape class creature you can also change into an undead or an normal beast.
Starting at level 10, your beast companion is immune to damage from any damage source it would normally be resistant too and has resistance to all non-magical attacks.
True Natural Terror
Starting at level 14, your animal companion can change to an undead up to CR 3.
And now a sorcerous origin!
You were not given power by birth, but by choice. A creature of power decided that you should be cared for and cultivated. You are not beholden to this creature in a bargain, but instead it gives this freely watching what you do with this gift. It follows you and helps, but you are still watched. Weather wanted or unwanted, you now have powers far beyond those that others would wield with no expectations on what you do with them. What destiny will you follow?
Starting at second level, you gain a companion. This creature must by of CR 1/2 or lower and either an aberration, celestial, dragon, elemental, fey, fiend, monstrosity, ooze, plant, or undead. You and your companion share a connection so you may give the creature mental commands, even when unconscious. These commands are limited in scope but as an action you can command the beast to take the Attack, Dash, Disengage, Dodge, or Help actions.
If you companion falls in combat, you may seek it out again by spending eight uninterrupted hours alone meditating and it will return.
Gifts of the Guardian
Starting at 6th level, each day you can choose a resistance your companion has and gain that resistance for a day.
In addition, you gain the ability to spend a sorcerer point as a bonus action to assign your companion an action.
Guidance from your Friend
At 14th level, any skill your companion is trained in is now a sill you are also trained in. If you were already trained in those skills, gains additional skill proficiencies equal to the ones it and you knew.
Beginning at 18th level, your companion changes to a different form and becomes a creature of the same time up to CR 3. Each day it can change its form at dawn or midnight.
Thoughts? Two in one day. What do you think?