Mercer Frey is the Breton leader of the Thieves Guild located in Riften and the primary antagonist of the Thieves Guild questline. He is also the owner of Riftweald Manor in Riften, although he is never actually found in or around this location.
Mercer joined the Thieves Guild at some point during the tenure of Guildmaster Gallus Desidenius. Mercer soon began skimming funds from the Guild's treasury, which was eventually discovered by Gallus. He took over the position of Guild leader after his predecessor Gallus Desidenius was supposedly murdered by Karliah, Mercer's former partner, until the Dragonborn discovered the truth while looking for Karliah with Mercer in tow in the ruins of Snow Veil Sanctum.
During the Dragonborn's initiation to the Guild, Mercer is usually the one that gives out tasks for them. It is noticeable from the beginning that he always acts impatient and irritated towards the Dragonborn. He shows obvious distaste towards them and becomes increasingly annoyed the more they progress in the Thieves Guild Questline. He eventually tries to kill the Dragonborn during "Speaking With Silence."
Mercer Frey is one of the quest characters that can be exploited to follow the Dragonborn throughout Skyrim along with a follower of their choice. In the quest "Speaking With Silence," after they enter Snow Veil Sanctum, they can leave and he will continue to follow them wherever they go.
This is a simple way to obtain a powerful follower as, whilst the mission is still available, he cannot be killed off by the Dragonborn or others. While it is not possible to converse or trade objects with him similar to an ordinary follower, he will remain an unkillable ally; at least until Karliah is found.
Mercer is generally quite pessimistic, stressed, and irritable. Despite his personality, he appears to be quite sly, for example killing the previous leader of the thieves guild, Gallus and blaming it on Karliah, and using her to lure the Dragonborn to Snow Veil Sanctum. He also seems to be adept in swordsmanship, as Karliah states when talking to Mercer, "Crossing blades with you would be a death sentence, Mercer."
He seems to be a master of sneak as he was able to silently approach Falmer and assassinate them swiftly while also sneaking past many of their Chaurus. This could possibly be the result of Mercer unlocking his hidden potential with the Skeleton Key. His lockpicking skill is debatable: he is seen picking locks that are unpickable, but this is almost certainly because he uses the Skeleton Key, which was in his possession at the time. It is also possible that he has generally good knowledge of the locks themselves.
As the true extent of his actions are revealed, Mercer is shown to be a man completely lacking in scruples both personal and moral, willing to betray and murder anyone who trusts him for personal profit. Over the course of more than twenty-five years, Mercer broke his sworn Oath to Nocturnal and stole the Skeleton Key, robbed the Thieves Guild blind, murdered his predecessor and pinned the blame on Karliah.
Mercer will assign the Dragonborn the first job in the Thieves Guild, which requires the Dragonborn to go to the Goldenglow Estate to teach the proprietor a lesson. Before going there, the Dragonborn can optionally talk to Vex in order to discover the location of the secret entrance to the estate.
After following Mercer inside the Snow Veil Sanctum, all the way to the word wall, he will attempt to end the Dragonborn's life. But Karliah saves them and nurses them back to life and will then reveal Mercer's treachery to the guild.
The Dragonborn travels to Irkngthand, a vast dwarven ruin that supposedly contains the legendary "Eyes of the Falmer." Karliah and Brynjolf are waiting for them within. Together they hope to stop Mercer Frey from stealing the Eyes and escaping from Skyrim with the Skeleton Key of Nocturnal.
The shelving behind Mercer's desk in the Cistern slowly fills with trophies relevant to any exploits and larceny targets sold to Delvin Mallory, such as the Left Eye of the Falmer. Those items can be taken from the cases. Upon finishing the additional jobs Delvin and Vex give the Dragonborn, trophies of recovered items begin to fill the shelves too:
- Jeweled Candlesticks appear after completing 5 jobs.
- An Ornate Drinking Horn after completing 15 jobs.
- A golden ship model appears after completing 25 jobs.
- A golden urn appears after completing 35 jobs.
- A jeweled goblet appears after completing 45 jobs.
- A jeweled pitcher appears after completing 55 jobs.
- A jeweled flagon appears after completing 75 jobs.
- After 125 jobs, a safe appears along the safe wall, next to the bookcases. It contains gems, gold and some thief potions.
- If the Thieves Guild quest "Darkness Returns" is completed, a shrine of Nocturnal appears in the Cistern. This bestows a Sneak blessing.
- After completing all four special city jobs, a chest appears in front of the desk in the Cistern. It is unlocked with the Guild Master's Tribute Chest Key, which can only be earned with the conclusion of the quest "Under New Management." It contains gold and gems and is periodically restocked.
- Mercer Frey is voiced by Stephen Russell, who also voices another thief, Garrett, from the Thief series, as well as Nick Valentine, a private detective from Fallout 4.
- Mercer's signature weapon is a Dwarven Sword of Devouring, which he supposedly stole from Irkngthand.
- During the final fight with him, a Dragonborn with a high sneak skill can hide from him, causing him to proclaim "The shadows are my domain!" This happens during any combat situation.
- Although he appears to teleport in the final fight with the Dragonborn, Mercer actually turns invisible for a few seconds while moving to a different spot in the room. While invisible, Mercer can be attacked and will not retaliate.
- During "Scoundrel's Folly," he will claim that Black-Briar Mead tastes like "swill."
This section contains bugs related to Mercer Frey. Before adding a bug to this list, consider the following:
- If Mercer is unable to follow the Dragonborn into Snow Veil Sanctum, Karliah will be stuck at the end of their argument, preventing the continuation of the quest.
- (No longer works on PC) When both Eyes of the Falmer are obtained from Mercer, it is possible to bring them back to the Thieves Guild and sell them to the fence, with the base price of 2,500 septims for each eye. After both eyes are sold to Tonilia, go talk to Delvin; there will be a speech option regarding the Eyes of Falmer. Select that dialogue and around 900 will be received even though the Eyes have already been sold. (The fence has her price set upward, 6,000 for the Eyes once she has them).
- Sometimes when downed during the quest "Speaking With Silence," he will not stand back up unless injured, then he will not open the door at the end of the quest.
- If Mercer is brought to the College of Winterhold while the unbound dremora from the "Conjuration Ritual Spell" quest is still around, he will openly attack the dremora but will be unable to do any damage to him for some reason. Also since Mercer will be openly hostile towards what is technically a resident of the College of Winterhold, all the other Mage residents will become hostile towards only Mercer, which results in an eternal fight.
- Mercer can sneak roll, but he still sets off tripwire and pressure plates even though for the Silent Roll perk the perk Light Foot is required.
- During the quest "Loud and Clear," obtained from Brynjolf when joining the Thieves Guild, if the Dragonborn does not speak to Brynjolf before entering the Ragged Flagon - Cistern, the Dragonborn is able to attack Mercer Frey repeatedly and neither he nor anyone else will become hostile.
- In "Speaking With Silence" Mercer may not open the first door into Snow Veil Sanctum. The problem may be circumvented by telling all followers (who can be told) to "wait here," at which point approaching the door should get Mercer to walk down the stairs, utter a comment about the ruins being impenetrable, and move forward to unlock the door. The problem occurs because no followers may enter the ruins, aside from Mercer.
- If the "Speaking With Silence" bug occurs, Mercer's facial expressions may also glitch.
- After opening the Nordic Puzzle Door in "Speaking With Silence," Mercer can be pickpocketed.