Tirrie is one of the water spirits found in the Water Ravine Dungeon along with Nirrie and Hallak.
According to the three water spirits, they have been on Gielinor as far back as the First Age. The trio share a united bond with one another in that they all share the same brain but are separate entities, which explains why they finish each other's sentences. Despite this, they are shown to be somewhat individual as during a conversation with them, Tirrie and Nirrie will point out that Hallak leaves the toilet seat up, to which he exclaims "It's supposed to be like that!".
They are not only responsible for killing the Saradominist monk who converted many of the citizens of Nardah from the Menaphite Pantheon, but were also responsible for drying up the water fountain prior to the events in the Spirits of the Elid quest. When asked why they dried up the fountain, they provide insight into their reasoning and explain the past alliance between Saradomin and Elidinis.
- It appears that when angered, they stop finishing each other's sentences. Players have an option to point this out to them, of which they explain that it happens when they get emotional.
- They reveal that the White golem, Grey golem and Black golem were gifts from Saradomonist mages as a diplomatic gesture which further supports the alliance between Elidinis and Saradomin.