In Christopher Paolini's Inheritance trilogy, the Agaeti Blodhren, or "Blood-Oath Celebration," is held every century in the Elven capital of Ellesméra to honor the bond created between the Elves and the Dragons. As with all celebrations held by the Alfakyn, Agaeti Blodhren is described as being "wondrously, gloriously mad". Participants relinquish control over their emotions, yet do not lose it; they throw caution and reserve to the winds, dancing and singing exuberantly. They leap and whirl, climb and bound, embrace and kiss freely. Gifts flow like drink from one person to the next. Lanterns are hung all over the trees. Several elves who have modified their bodies in various ways using magic appear at the ceremony. The highlight of the long festival is the ceremony of gift-giving, in which each attendant presents the fruition of some project or the other, such as a sculpture or a poem.

Nearing the end of the Blood-oath Celebration that Eragon observed, he watches a ritual that involves two female elves undressing (and giving young Eragon a lap dance) to reveal a full body tattoo that goes from one body to the next. They dance to create the illusion that the dragon tattoo is dancing and alive, and the tattoo becomes a dragon spirit which heals every scar Eragon had ever gotten in his life, including the scar given to him by Durza, and also the terrible spouts of pain that had come along with it. Eragon instantly takes on all the physical attributes that a Rider normally develops over a long period of time, becoming something like a human-elf hybrid, with some human features but increased senses, power and other characteristics that overall improve his strength.

His face was now smooth and angled as an elf's, with ears tapered like theirs and eyes slanted like theirs, and his skin was as pale as alabaster and seemed to emit a faint glow, as if with the sheen of magic...Yet he was not entirely an elf. His jaw was stronger, his brow thicker, his face broader. He was fairer than any human and more rugged than any elf...Eragon floated in a state of heightened awareness, his senses thrumming with the multitude of new sights, sounds, smells, and feelings that asailed him. He could see in darkness that would have blinded him before. He could touch a leaf and, by touch alone, count the individual hairs that grew upon it. He could identify the odors wafting about him as well as a wolf or a dragon...the beating of his heart was a drum to him.
- as paraphrased from pages 471-472 of Hardcover Eldest

Many critics of Eldest have labeled this scene as a poorly done Deus ex machina. Others note that the nature of the celebration seems to be akin to psychodelic, drug-induced experiences.