Fae Heart Plates

"Hearts of Silver joined in love, a friendship forged from life's first blood. Though we may have waited to meet, our souls recognize each other, what a treat. Though these bodies do not feel the longing, our souls, our minds, to each other are belonging."

The Oath of Silver, the Promise of Friendship.

"Hearts of Crimson Red they run, our blood, our love a rush that cannot be undone. Our longing equalled only by our trust. Our desires for one another never equalled until all is dust. We are two, we are one. We belong together, a love never undone. For now and forever, we are the joy. That each other brings pleasure, love and toy. Our spark is eternal, our love unbowed. From now til forever, we swear it, to be bound.

The Oath of Red, the Promise of Romance

These are exceedingly rare artifacts that even in their time, millenia upon millenia ago before the Sundering and the end and the rebirth of Valerick. From the time that the Fae Folk, and their great houses and fiefdoms of the Aether and the Weave of Dreams also ruled the Material Realms. From a time when magick was stable, safe, even easy. Such powerful magicks as this, though pricey, were far more normal in all likelihood.

These plates, only two sets that function having ever been discovered, it is theorized from limited scholarly records and context clues based upon the oaths within, were a sort of ceremonial contract in magick form, similar in some ways to an oath of sworn familial ties, brother/sisterhood, or even marriage. However with much greater powers it would seem, for in recent memory one of the two intact sets discovered were used.

Upon being bonded, based upon the oath the pair swore, the two plates, both shaped like a heart, will join, and then shift color to match the oath. Then the now fused metal heart will crack in half and melt themselves, melting into the torso of the two people, becoming as if a magick tattoo. Amongst the storied benefits, one that is known to exist, for the two individuals whom discovered the first ever set and used them had this happen....they can return a fallen partner to life, though they will draw life energy from the survivor to do it, inflicting a great deal of pain upon them.

Game Mechanic Stuff

So these items in a DnD 5e sense would eat one attunement slot of both individuals until they are broken via the death of one of the partners. They cannot, to current knowledge, be removed any other way. If Pathfinder 2e they are kind of cursed in a sense that you cannot remove them and they take up either your torso or your back slot (so no armor or no cloak). The benefits are noted below;

Oath	DnD 5e Benefits	Pathfinder 2e Benefits
Friendship	Have your Back!: When within 30 feet of each other, have advantage on Saving Throws	Have your Back!: When within 30 feet of each other, have +1/4 your level to all Saving throws (minimum 1) and to AC
Romance	Protective Instinct: Whenever your partner takes damage that you see or hear them cry out in pain, gain advantage on all your attacks for 1 round. Can only trigger 1/round	Protective Instinct: Whenever your partner takes damage that you see or hear them cry out in pain, gain +1/4 your level (minimum 1) to your attack and damage rolls for 1 round. Can only trigger 1/round.

Broken-Hearted

Beyond these noted benefits these objects provide one other potential benefit. Once bonded, should one partner die, the surviving partner suffers a Broken Heart. The terms of this are similar but not the same for both game systems I use so I shall dictate them both below. Naturally improvise the terms as needed for the game you are running as always.

DnD 5e:

So for this ruleset when one partner dies, the survivor immediately makes a DC 20 Constitution Saving Throw. Should they succeed, they immediately take damage equal to half their current HP, but their partner returns to life with that same amount of hp. The tattoos fade away, gone forever, freeing up the Attunement slot, and the pair keep the base oath benefit forever, but without any way to bring each other back in the future, and should one of them die the survior is afflicted with the Curse of the Broken Heart. Should they fail the saving throw, the plates fade away, gone forever, and the dead partner cannot be returned to life by any means beyond first a Wish spell to extract their soul from the fabric of the Feywylde, and then true resurrection. The surviving partner suffers the Curse of the Broken Heart, which cannot be removed by any means save Wish.

Pathfinder 2e:

So for this ruleset when one partner dies, the survivor immediately makes a DC 22 Fortitude Save. If they critically succeed, they suffer no damage, the heart plates still fade away, but their partner returns to life at half their maximum hp with no Wounded conditions. If they normal succeed, they take damage equal to 1/2 their current HP and the partner returns to life with that much HP and no Wounded Conditions. The heart plates fade away. If they fail, they take damage equal to 1/2 their Maximum hp, and their partner returns to life with that many hit points and Wounded (1). The heart plates fade. If they critically fail, the heart plates fade away and the partner is dead forever, able to be brought back by no other means. The survivor suffers the Curse of the Broken Heart, which cannot be removed by any means save Wish. In all cases where both partners are alive after this is resolved, the base effect of their Oath as well as the Broken Heart is still in effect, meaning when one of them eventually dies and cannot be brought back, the survivor suffers the Curse of the Broken Heart.

Curse of the Broken Heart

In both systems this is a steep curse, inflicting a permanent -2 to the Constitution Score and -4 to Charisma Score of the survivor.