Fearless Units containing one or more models with the Fearless special rule automatically pass Pinning, Fear, Regroup tests and Morale checks, but cannot Go to Ground and cannot choose to fail a Morale check due to the Our Weapons Are Useless rule. If a unit has Gone to Ground and then gains the Fearless special rule, all the effects of Go to Ground are immediately cancelled.
Reanimation Protocols When a model with this special rule suffers an unsaved Wound, it can make a special Reanimation Protocols roll to avoid being wounded. This is not a saving throw and so can be used against attacks that state 'no saves of any kind are allowed'. Reanimation Protocols rolls may even be taken against hits with the Instant Death special rule, but cannot be used against hits from Destroyer weapons or any special rule or attack that states that the model is 'removed from play'.
Roll a D6 each time the model suffers an unsaved Wound, subtracting 1 from the result if the hit that inflicted the Wound had the Instant Death special rule. On a 5+, discount the unsaved Wound - treat it as having been saved. Certain special rules and wargear items can provide modifiers to this dice roll; these are cumulative, but the required dice roll can never be improved to be better than 4+.
If a unit has both the Reanimation Protocols and Feel No Pain special rules, you can choose to use one special rule or the other to attempt to avoid the Wound, but not both. Choose which of the two special rules you will use each time a model suffers an unsaved Wound.