Hallgrimsson had met Lord Asriel at the university some time before he and Axel Löfgren encountered Marisa Coulter. She came to consult Löfgren about the Rusakov field and both were taken by her beauty and intelligence. Mrs Coulter was also interested in consulting the Uppsala alethiometer about her daughter; Hallgrimsson later overheard from her servants that this was prompted by a prophecy of the witches.
Around a month later, he and Löfgren were joined by Coram van Texel at the university, introduced by a letter from Martin Lanselius. Coram encouraged Hallgrimsson to tell him about the alethiometer, learning about the state of mind needed to read it and the whereabouts of the six believed to have been made. Hallgrimsson told the story of how the Bodleian alethiometer avoided falling into the Constistorial Court's hands and reported that the principle scholar of the alethiometer at Uppsala was apparently on a sabbatical term at the Bibliothèque Nationale in Paris. Coram also learnt of Marisa Coulter's enquiries and presence at the university.
Hallgrimsson was a bachelor, sharp-witted and rather nosy. He seemed to enjoy gossip. The study where he met with Coram van Texel was notably comfortable and Hallgrimsson had a case of Tokay sent from Buda-Pesth every year, suggesting he enjoyed his luxuries.
Hallgrimsson's dæmon was a robin. When meeting with Coram van Texel, the dæmon said very little and sat on his shoulder.