Kolya is a very highly esteemed cook who was the proprietor of "The Beefy Bob", a restaurant in Dany. He used to run this restaurant with his two favourite waiters Anya and Viktor. However, after his restaurant was raided a couple of times by Grubmillian soldiers during King Elmer's brief invasion of the queendom, he decided to call it quits.
Kolya is good friends with his drinking buddy Wim. Wim still visits Kolya from time to time to drink wine and talk about just everything.
Recruiting Kolya will open a brand new restaurant at your castle, serving high quality food to everyone there. Much to the relief of Wim, his restaurant comes included with a pub. You can order food items at the counter of Kolya's restaurant. Normally, a restorative item restores either health OR cures a status ailments. Food items do both. So it's definitely a good idea to bring some of them with you. You can actually expand Kolya's menu by bringing him recipes acquired in your journey.
Kolya can also travel with you. After every battle that has lasted at least 5 turns, he will surprise you with a free dish.