Followers are essentially the new mercs. There are some differences, however. This time around, they are specific, story driven characters that join your quest as the game progresses. Each one has their own story, background, and distinct personality. Gameplay wise, they each fill a different roll in combat, can be equipped with a main and off hand weapon, two rings, and an amulet, and will level up along side you. At levels 5, 10, 15, and 20, they unlock a new teir of skills. Each tier has two skills, and you choose one of them. You can respec them, free of charge. At level 25 they gain acceess to a class-specific gear slot. They also get 20% of the Magic or Gold Find from gear, which is applied to your total while they are active. You can only have 1 follower active at a time, and only while playing solo. If someone joins your game while you have a follower active, they will simply salute you and head back to town.
The three Followers are:
Kormac, the Templar.
The tank. Doesn't deal out much damage, but serves as an excellent meat sheild. Can use shields, one-handed axes, daggers, one-handed maces, one-handed spears, one-handed swords, and the Templar specific relics.
Lyndon, the Scoundrel
Ranged pysical damage dealer. Can use bows, two-handed crossbows, and the Scoundrel specific Tokens. Also has an excellently-groomed mustache.
Eirena, the Enchantress
Ranged magic dealer, casts buffs and debuffs. Can use two-handed staves, two-handed swords, two-handed maces, or two-handed axes, and the Enchantress specific Focuses.