Jacob

Jacob first appears in Rise of the Tomb Raider as a prisoner in the Gulag. There he meets and befriends Lara Croft, who frees him from his cell in exchange for information regarding the Divine Source.

During their escape from relentless Trinity forces, Jacob saves Lara's life after she nearly drowns. Lara believes Jacob to be a good man, however, she acquires the feeling "he knows more than he's letting on."

Later, Jacob and Lara traverse through the old copper mines, however, they are separated and Lara is forced to make her way to the Remnant Valley alone where she encounters a hostile Sofia, who nearly kills Lara when she suspects she killed Jacob. However, Jacob arrived just in time to vouch for Lara, ordering his people that "no harm will come to her."

It is later revealed that Jacob is just another alias used by the Deathless Prophet, who has been alive for generations, living with the remnants in the valleys and mountains that surround the Lost City of Kitezh.

Death
Ultimately, when Trinity besieged the ruins of Kitezh one final time, Jacob arrived at the Chamber of Souls, only to be shot several times by Ana.

After Lara destroys the Divine Source, Jacob returns to his mortal self and tells Lara he's never met anyone as extraordinary as herself in all his time, and thanks her for making this difference before he peacefully disintegrates.

Powers & Abilities

 * Supernatural Powers: He was exposed to the "Divine Source" and therefore gained ageless immortality, unlimited stamina & extreme regenerative powers, that resurrect him from death. Through practice over using his powers, he also learned how to heal any mortal being within several seconds, just by using the limitless regenerative energies inside his body. These "Divine" powers, seems to have also made him stronger, faster & durable than an average human being.
 * Warfare Expert: Like most of his people, he too is a highly skilled guerrilla fighter, marksman, stealth tactics, craftsman & hand-to-hand combatant.

Trivia

 * After finishing the game, some villagers around the valley can be overheard talking about Jacob and the source, one saying "Jacob and the source are gone, what are we protecting now" meaning they all knew about Jacob, he hadn't tried to keep himself and his immortality a secret to his people.
 * When it is revealed that he is the Prophet, Jacob tells Lara that he can still "feel pain, that he is still human, just without the human end."
 * At the end of the game, when the player returns to the ruins of Kitezh, the Deathless Ones are still encountered instead of Trinity soldiers. Either this means that some power of the Divine Source is still active, or the game developers overlooked this so the player could fight the Deathless Ones at anytime. There is a slim chance that Jacob is still alive even if the former is true, as he had completely turned to dust.
 * Jacob's voice actor is Philip Anthony-Rodriguez, who also voiced for Fallout 4, which had come out at the same time as Rise of the Tomb Raider.