The Besties trophy / achievement in God of War Ragnarok is unlocked after completing the Animal Instincts favor in Midgard. You need to defeat the raiders who once imprisoned Speki and Svanna, two of the wolves rescued by Kratos and Atreus. These particular wolves are the ones who pull the sled as you travel around Midgard, and you will have the opportunity to pet them at the end of the favor when you return to them.

Besties

Pet Speki and Svanna