The first level of Empathy allows a Dragoon to copy one status effect to his or her wyvern each time Spirit Link is used. Each subsequent level of Empathy copies one additional status effect (so Empathy level 2 copies two effects each Spirit Link, while level 3 copies 3, and so on).
The status effects that are copied are chosen at random from all the compatible status effects on the Dragoon.
Status effects can be copied regardless of whether they are currently active on the wyvern or not, so the same status effect can be copied and overwritten multiple times.
The copied effects have a duration equal to the time remaining on the original status effect (so the effects on the wyvern and the dragoon will typically wear off at the same time).
Empathy allows Dragoons to use Spirit Link when his or her wyvern is at full health. Using Spirit Link this way does not consume any of the Dragoon's HP.