Thanks to Deowulf-Dragonblight, Ariennelenna-Dragonblight, and Sita-Fenris, the secret of Courage has been solved! [source]
Courage is a shy larion cub, but can be coaxed out at Nemea's Retreat (slight northeast of Hero's Rest, above ground).
There are a total of 9 larion cubs at Nemea's Retreat. Gather enough players to interact with these cubs at the same time and Courage will appear.
Initially, it was believed that all 9 cubs needed to be interacted with at the same time. However, Wowhead has tested this further and found only 5 out of the 9 cubs need to be pet at the same time.
A couple of cubs are hovering and may seem out of range, but it's possible to pet them if you jump up and quickly click on them.
Pet 5 out of 9 larion cubs simultaneously and Courage will emote and appear next to Nemea for a short period of time (about 30-40 seconds). Interacting with Courage (NPC) will add the battle pet directly into your Pet journal. You don't need to have participated in the summoning to collect Courage, simply be present when the NPC spawns.
We're ecstatic that Courage has finally been found! Happy collecting!
I already have one Courage but I could not get a second pet, so may there is a maximum of one and not three pets
You need to pet 5 larion cubs almost simultaneously.
It CAN be done with a group of four players (since we just did it in the 2nd try)
Courage was there for only maybe 1 minute.
Pet #1212: Courage :D
2 days ago I go to the hill with Nemea and search for a group for Courage, and find it. When we are 9, 8 of them were next to a laryon ready to click in GO after the timer, and Courage spawns next Nemea (mouseover is a gear).
Is there a discord channel for Pet collectors to find people to do this?