Cesar is a merchant, plying his trade around the central bazaar of the Denerim Market District. The Warden can find him to the right of the bear cages under the tent in the center of the district next to Master Ignacio.
Involvement
He is a merchant, selling goods to the Warden. After completing The Trial of Crows, Cesar will have a "special stock" available to the Warden. He also maintains substantial connections to the Antivan Crows and possibly works for them as well.
If the Warden kills Master Ignacio, Cesar will permanently vanish.
Inventory
Name Price 
Magebane Poison Recipe
4 
65
60
Soldier's Bane Recipe
4 44 0
Demonic Poison Recipe
3 40 80
Concentrated Crow Poison Recipe
2 73 60
Concentrator Agent (x2)
36 0
Demonic Ichor (x3)
24 0
Corrupter Agent (x4)
14 40
Deathroot (x4)
1 20
Toxin Extract (x3)
1 20
Ash Warrior Axe
6 79
Crow Dagger
13 20
Saw Sword
14 40
Barbarian Mace
1 24 80
Orlesian Bow
20 40
Fire Arrow (x40)
15 84
Ice Arrow (x40)
15 84
Enchanter's Staff
3 48 0
Barbarian Helmet
3 96 0
Qunari Infantry Helm
4 62 0
Crow Shield
14 40
Clan Shield
14 40
Tevinter Shield
1 25 92
Inventory 'Special Stock'
Name Price Concentrated Magebane Recipe
8 94 0
Concentrated Soldier's Bane Recipe
8 58 0
Concentrated Demonic Poison Recipe
8 46 0
Quiet Death Recipe
6 54 0
Concentrator Agent (x4)
36 0
Demonic Ichor (x4)
24 0
Corrupter Agent (x5)
14 40
Deathroot (x7)
1 20
Toxin Extract (x8)
1 20
Dwarven Waraxe
7 59
Barbarian Axe
15 60
Dar'Misu
12 0
Qunari Sword
1 72 80
Saw Sword
14 40
Heavy Maul
1 58 35
Orlesian Bow
20 40
Antivan Longbow
38 79
Antivan Crossbow
14 79
Explosive Bolt (x20)
31 68
Fire Bolt (x40)
23 76
Arrow of Filth (x40)
23 76
Ice Bolt (x40)
23 76
Knockback Bolt (x20)
19 80
Fire Arrow (x40)
15 84
Ice Arrow (x40)
15 84
Magic Staff
78 0
Executioner's Helm
66 0
Qunari Commander Helm
24 0
Knight-Commander's Helm
49 20
First Enchanter Robes
5 40 0
Grandmaster Dweomer Rune
11 10 0