Found: They can be purchased from John Smythn in the Hall of Heroes. You must be no lower than one level beneath the henchman's level in order to hire him/her.
About: You can also hire other followers, these however will not "auto level up" with you, so purchase them when you are at or below their level and NEVER remove them from party if you wish to use them. Also, past a certain lv (Henchmen lv 5) you will not find anyone worth purchasing as their allocation becomes more and more "beyond repair", this means the window to purchasing these henchmen is between levels 2-5, which is a very small window... There are only a couple that should potentially draw your attention:
Berthold "The Barrel"
Cleric Level 2
+1 Shield Specialist
+1 Armor Specialist
Thoughts: If you hurry with your initial Star stones you can get to him at around lv 2. If you hate Jahan, Berthold will build into Dual Wizard just as well if not better than Jahan if you really wanted two of them. He comes with "Stench" and no Spd, just give him the "Glass Cannon" talent to help with his AP needs and put the last secondary stat point into Con as well.
Thoughts: Fantastic contender for Shadowblade! Perfect stats and talents with decent skills makes her the best choice for Shadowblade Jahan alternative in the game.
What a Rush
Far Out Man
Thoughts: Frankly might be the best follower in the entire game... Great stat, great skills, and great talents and laid out in such a way that you could build any direction you wanted! Ranger/Dual Mace Wizard/Shadowblade you can build into basically flawlessly. If you hate one or more of the unique followers, Sondre is an easy "opt out"...
Far Out Man
Walk It Off
Elessa is currently glitched out. For a level 7 character Elessa comes with 15 more ability points than a lv 7 should have- even more than a "lone wolf" would have at this point. Don't know how much longer she will be around in her broken condition or if I will honestly ever use her because she is so broken, but here she is!
There are four semi unique companions in the game. They are the only four who will auto-level up with you, as well as all having a single unique quest tied to them as well as unique banter, they are:
Found: in the King Crab Tavern in Cyseal.
Stats: +3 Str, +2 Con, +1 Spd
Skills: +2 Two-Handed, +2 Man-at-Arms, +1 Bodybuilding
Talents: Comeback Kid, Opportunist, What a Rush
Best Class: Two-Handed Knight A+
Thoughts: Madora comes with "comeback kid" which cannot normally be taken until one has 5 points invested into willpower, this is a huge boon. She also comes with her stats perfectly allocated- because of those two facts she literally is the best two handed leadership knight in the game, even better than source hunters as source hunters wouldn't get the "comeback kid" for free. If you want a two handed leadership knight build in your party do not make your source hunter one, pick up Madora... If you are going "lone wolf" and don't pick up Madora, remember to pick up leadership skill on your lone wolf!
Found: found in the Library in Cyseal; on the second floor of the mayor's house.
Stats: +3 Int, +2 Con, +1 Per
Skills: +1 Willpower, +2 Aerotheurge, +2 Hydrosophist
Talents: Scientist, Far-out-Man, Elemental Affinity
Best Class: Dual Wizard C+/Shadowblade A
Thoughts: Great skill allocation with decent talents and stats. The +1 Per can easily be changed to a +1 Int with a unique book found in game, that means that his stats end game as a Shadowblade are flawless. Because of this Jahan makes a perfect Shadowblade (unique daggers will give +6 Spd end game so Shadowblades can afford to have Con as a secondary vs Spd). Because of Jahan's ability to build into Shadowblade so easily as well as being one of the four unique followers (they auto level up with you) Jahan should most likely be one of your two followers.
Found: in the tunnel at the cemetery, in Cyseal; or down the well directly out the west gate.
Stats: +3 Spd, +2 Dex, +2 Per
Skills: +2 Dual Wielding, +2 Scoundrel, +1 Lockpicking, +1 Pickpocketing, +1 Sneaking
Talents: Backstabbing, Light Stepper, Escapist
Best Class: Shadowblade B (B if you use two unique books, C- if not)
Thoughts: Terrible stats, not great skills, and two talents wasted makes Wolgraff one of the worst if not the worst spec'd of the four. If you can find two of the unique books and gives a +1 to Int at the cost of -1 Per you can turn his stats somewhat around so that as a Shadowblade he will end up with his 11/11 in Int/Dex (don't add any more points to Spd!) but that will also mean that you would have an ultra-glass cannon on your hands for no damn good reason...
Found: jailed near the Legion Headquarters in Cyseal.
Stats: +2 Dex, +2 Con, +1 Spd, +1 Per
Skills: +1 Bow, +1 Tenebrium, +1 Loremaster, +2 Expert Marksman
Talents: Arrow Recovery, Bully, Stench
Best Class: Ranger C-?
Thoughts: The worst stat allocation of the four without a doubt, with decent skills and talents makes Bairdotr contender for worst of the four. No matter what you do Bairdotr will not end up with 11/11 in her primary stats which means she will end up being be a terrible spell caster and a subpar bow user or simply just a very strong bow user with no other redeeming qualities. Of the four she gets my "most likely to be turned into a crafting mule" as she already has a point in loremaster and tenebrium. Ranger is the most powerful build in the game and Bairdotr doesn't cut it; it would be well for you to avoid Bairdotr and make one of your main two source hunters a ranger built from the ground up. Also, if you are not careful *SPOILER* Bairdotr can and will leave the party and try to kill you!