Nigel is apparently dependent on Sebastian for survival, and will protect his conjoined twin above all else. However, Sebastian is fully capable (if crippled) of surviving without Nigel.
They are initially seen gnawing on the head of a struggling mutant. Upon spotting the players, Sebastian commands Nigel to attack, excited by the prospect of "good eats".
On record, Sebastian is the only zombie capable with an intelligent speech, besides from having a number of teeth missing.
Nigel and Sebastian are conjoined twins that have somehow been mutated by the formula. Nigel is a dim-witted giant roughly three times the size of the average human, while Sebastian is a well-versed tumor-like growth protruding from his stomach. Nigel fully relies on Sebastian because they both share the same organs so attacking him will weaken them.
During the battle, he will come out in front of you. You need to shoot Sebastian to make him recoil.
After the Battle
Isaac and G presume the duo to be dead and begin to converse on the repulsive nature of this particular mutant. Both are disgusted and shocked to see that Sebastian is still clinging to life, and the two comically pepper his prone body with a torrent of bullets before they ride away in an ice cream truck discovered by G.
Extended Cut differences
As we note the extended cut version of Nigel and Sebastian is different from the original
- Nigel has more developed arm muscles he has teeth and a mouth filled with blood, while Sebastian's head is completely different and has pupils as the stage is clearer and more detailed. In the extended cut version, Nigel follows you around, then comes towards you, and when they die instead of falling face down, they fall down on their back. These movements are unique in the extended cut versions:
- Two punch: Nigel hits you with his 2 hands (which causes double damage) is made after two normal attack.
- Call the clown: Clowns come to attack you, unlike the original version, the clowns running target move underside of somersaults, and underside of passing through walls, jump over them, deputes to attack from front, three target behind the player.
- Hyper jump: While the player kills three clowns behind him, Nigel and Sebastian climb to the roof and throw to attack, to avoid attack is to shoot at targets, unlike the original version, underside of Nigel and Sebastian fall in front of the player, fall to the right of the player.