Griggs is trapped in a room while caught exploring. He has been searching for his master but cannot find him. After his rescue by the player, he expresses his gratitude by selling the player sorceries.
Griggs' ultimate goal is finding Big Hat Logan, and they do indeed get reunited if the player did not purchase all of Griggs' items before rescuing Logan. However, Logan will leave again, leaving Griggs with some of his knowledge. Depending on the player's actions, Griggs will then be hollowed in Sen's Fortress, or remain in Firelink Shrine until the end of the game.
Not much is known about Griggs. Judging from Rickert's claims that Big Hat Logan was a hundred years before his time, it can be assumed that either Rickert is a hundred years in the future, or that Logan (and thus Griggs) are from a hundred years ago and ended up in the present timeline due to Lordran's time warping.
He wears the Black Sorcerer Set. In Vinheim, the Sorcerers who wear Black Sorcerer set are often secret members of the Dragon School.
Somebody! Please, let me out of here! Somebody, anybody! Help me! Unlock the door! ...Damn... ...I'm finished... How did this ever happen...
Brilliant! You opened the door for me! Thank you; I am saved. I thought I might never escape. I am Griggs of Vinheim. A sorcerer of the school. I am much obliged for your assistance. Thanks to you, I may now resume my travels.
Talk after freeing him
Oh, hello. I am fine. I will rest a while, then return to Firelink Shrine. I have my sorcery. And I will be more cautious next time. Besides, I have an important task at hand.
Speaking with less than 10 intelligence
Oh, hello. Terrific to see us both in one piece. And pray that you never go Hollow!
Back at Firelink
Oh, hello. I regret meeting you under such compromising circumstances. At least we both made it back unscathed. Incidentally, would you care to learn any sorceries? You're clearly talented, and besides, I owe you. Of course we will require some materials, but I am happy to teach you some elementary spells. Are you interested?
Splendid! Very well! I am pleased to have a chance to give something back. Well, then lets get started straight away.
It's not that I am concerned for Master Logan's welfare. Even in this treacherous land, Logan's skills are unmatched. He is a true hero. ...No, the reason I seek Logan is... ...Well, it's really my own conceit, now isn't it?
Farewell without any purchase
Good-bye, then. Do stay safe.
Farewell after making a purchase
All right. That'll do it. That should help you on your journey. May we meet again.
Greetings after Rhea and her companions leave
Did you see them? The three young clerics... headed for the Catacombs, to seek Kindling. Kindling is the art of feeding bonfires. The poor young girl, sent down into a tomb. What a terrible mission she is burdened with.
Greetings after Logan has left
Oh, there you are! Just so you know... Master Logan has left on his own again. It seems that he is still determined to find the famed Regal Archives in Anor Londo. I intend to search for him. Only, before I leave, there is one thing I wish to do. You see, Master Logan has left most of his books. With them I could teach you Logan's sorcery. ...You have done much to assist me. Before I leave on this journey, I will teach you all that Logan has to share.
After Logan has left
Oh, hello, you made it! Then, let us begin. As promised, I shall bequeath Master Logan's sorcery to you.
Curses, you leave me no choice! You aren't yourself any more. Forgive me!