Fremennik names are given to a player at the end of The Fremennik Trialsquest. This name accompanies the player throughout the whole RuneScape game, unless it is changed with the ring of charos (a). Using the power of the ring of charos (a), players may ask Brundt the Chieftain for the Fremennik name to be changed. Doing so yields a new random name for that player.
Names do not appear to be gender specific as some have been assigned to both genders (e.g. Rakkir, Raktor, Thorrak, Tonkar). Also, it appears as though names are generated by using one of 16 different prefixes (Bal, Bar, Dal, Dar, Den, Dok, Jar, Jik, Lar, Rak, Ral, Ril, Sig, Tal, Thor, and Ton) and one of 16 different suffixes (dar, dor, dur, kal, kar, kir, kur, lah, lak, lim, lor, rak, tin, ton, tor, and vald). That would indicate potentially 272 different Fremennik names are available.
Baldur is the god of male beauty and light in Norse mythology. It is also a reference to the Dungeons and Dragons game Baldur's Gate.
If players switch genders after receiving their Fremennik name, they will keep the Fremennik name.
There is a bug where Fremennik names change on their own, where an extra suffix is added, for example "Thorvald" changing to "Thorkarvald", all on its own. This rare bug has existed for many years, and Jagex is yet to patch it. The only way to fix the effects of this bug is to change your Fremennik name with a ring of charos (a), receiving a random name.
Jarvald and Thorvald, which are possible names, are also names of Fremennik NPCs.