Brennivin was the Mysterious Man in the chance item
Dark Reflection in August 2009. Those playing the Dark Reflection CI were sent to an Alternate Gaia to search for Kanoko, who had been
sucked into a magical mirror that had fallen out of a cart that Radio Jack was driving. Upon meeting an alternate version of a Gaia NPC, Gaians had the option to stop and receive an item or to continue to search for Kanoko. There was a chance that Gaians would run into a Mysterious Man (the owner of the mirror), who would automatically end the search.
Artwork from Dark Reflection can be found in
this thread.
In July 2012, Brennivin was the instigator of the
Runic Challenge CI: "Summer showers - you can never predict them. Thanks to inclement weather, our friends Radio Jack and Kanoko are stuck inside Dernier Cri with nothing to keep them entertained. Their boss, Brennivin, suggests a friendly board game to keep them busy as the storm passes.
"Of course, nothing is ever as it seems with Brennivin. With a cryptically uttered spell, he transports them into the world of his favorite game board game, Runic Challenge. To make matters worse, it seems the only way back out is to complete the game! Who or what will our favorite trio from Dernier Cri see along the way?"
The art thread for Runic Challenge can be found
here.
Brennivin starred in the
Impractical Gala CI in January 2013 in which he accepts an invitation to the wizard's ball and meets wizards from other times.

"Vá! Laglegur Gaian, look! I received invitation!
"An awe-inspiring gala, with wizards and other magical kin anticipated from across Gaian timeline! Many gather centennially for djammið at castle, outside temporal universe, to storytell and trade new invented spells!
"AND they wear their fashionable clothes of all ages and different places... Hvetjandi, já! <3<3<3
"I always have +1 privilege, but I've never used... Maybe this time you want to be my companion?
"I must uh... 'hobnob,' a bit, þú veist... But you'll find friends, I can safely say!"
One of the wizards that can be encountered when playing the CI is Auldivin the Stonehand, Brennivin's father:

"As you work up the nerve to speak to the magical folk, you’re startled by a strange mewling noise. You suddenly find yourself in the shadow of a looming, aged wizard with a grim expression... And a solid grip on a very distressed Brennivin. 'You there!' the old wizard growls, his lips not quite matching his words (an advanced translation spell, you suppose?) 'Are you harassing the guests like your brat friend here?! I’ll turn you BOTH into beetles for this!' Thinking quickly, you reply, 'I’ve never seen that guy before in my life!'
"Despite the murderous look Bren shoots you as he’s dragged away by his ear, you don’t let yourself feel that guilty. You figure he’s probably used to getting turned into weird things by his scary dad. Although you might be a little worried that your ride home is probably a beetle by now."
The art thread for Impractical Gala can be found
here.
The February 2014 CI
In Deep Ship had art featuring Brennivin in a crack (?) ship with Stein.
The art thread for In Deep Ship can be found
here.
In June 2014, Brennivin went to a con in the
CON Tagious CI. "Oh it looks like its Con season Gaians! Your favorite fashionable conjurer Brennivin is attending the local convention for the first time! He’s looking around at all the amazing costumes for a little bit of inspiration! Comb the con halls, takes some pics and maybe you’ll run into an old familiar face…"
See if you can spot Brennivin in each picture!
The art thread for CON Tagious can be found
here.