Some time later, Triss found out about her friend's relations with Geralt of Rivia. Curious about the nature of that relationship, she used a little bit of magic and seduced the witcher, resulting in short relationship between them.

After some time however, Geralt simply ended the relationship from guilt. This proved to be very difficult for Triss as she fell in deep love with Geralt. Despite that, the two of them remained very good friends in years to come and even though Triss was still unhappily in love with him, he did not wish to start anew.

In 1263, after the First Northern War with Nilfgaard started, and the kingdom of Cintra destroyed, sorcerers and sorceresses under the leadership of Vilgefortz of Roggeveen decided to stand on Sodden Hill supporting Northern troops with their magic. Here, they wanted to stop the invading forces. Triss was among those who volunteered. The battle was brutal and the mages stood against incredibly strong forces but in the end, they managed to defeat the invaders. The cost of victory was high, though, as 13 mages died. As a matter of fact, it was first believed that the number of dead was 14 - the last one being Triss. She was very seriously wounded, sustaining burns on her body, but also having all of her hair burnt off. With Yennefer, the only mage that would have still recognised her, blinded during the battle, she was counted amongst the dead.

When Geralt rode near Sodden some time later, he saw the memory stone erected in remembrance of those who gave their lives to protect the North. Triss was among them, which saddened Geralt very deeply. When it was later discovered that Triss had indeed managed to survive the battle, she became known as "the fourteenth of the hill".

In December 1265, Triss received a message from Geralt, asking her to come to Kaer Morhen to help him with his Child of Surprise - Ciri. Ciri was trained by the witchers, yet she started to show some strong magical abilities that were beyond what was conventional for witchers. Thus, Triss accepted and went there, but she was reluctant to be near Geralt again as her feelings for him had not faded. During her stay, she constantly struggled with the way she felt, but eventually managed to clear her mind and do her job. Ciri, as she discovered, was a young lady with a sad history and the two of them took a liking to each other instantly. Their bond was so strong that Ciri started to consider Triss her older sister and vice versa. Some disquiet between Triss and the witchers surfaced when Triss discovered that the witchers wanted to submit Ciri to special potions. While not as invasive as the Trial of the Grasses, the potions would still cause harm to her body and most likely leave her barren. She begged them not to give her those, and eventually they agreed.

The other problem was that Ciri slowly became a woman and, being only girl in the keep, she had nobody to ask about specifics that comes with that. When Triss discovered that Ciri had no idea about her own cycles and that the witchers were unaware of them as well, she was furious. Since then, whenever Ciri came in dress, the training would stop until she change to the training attire.

More problematic, however, was her increasingly strong proficiency with magic. The witchers told Triss, that since Ciri came to the keep, she had 3 incidents where she spoke with a different voice in an unrecognizable language and entered a trance-like state. In the last one, she also foretold the deatsh of Geralt and Coën. They said that the first time it happened was after Ciri accidently drunk a potion, the same potion, that now stood before Triss. When Ciri came, Triss tricked her into drinking said potion to the shock of all the witchers. She told them however, that she knew what she was doing, and she wished to understand the trances. Ciri started to dance and not long after fell into a trance. Triss telepathically connected with her and tried to find out the problem. While connected to the young girl, she felt a strong presence inside her, hallucinating that she was back at the Battle of Sodden Hill. Triss used all her power and identification spells but it all proved futile. This battle of wills proved very draining and she passed out.

Later, she woke in her bed with Geralt next to her. He told Triss that she was out for six hours and ensured her that Ciri was alright and slept in her room. The sorceress told Geralt that whatever was wrong with Ciri was way too powerful for her and that he should contact Yennefer, who was more knowledgable about such things. Geralt was reluctant, considering their past, but Triss insisted it would be the best for the girl. After Geralt agreed, Triss told him that when spring came, they should take Ciri to the Temple of Melitele in Ellander. The witcher agreed and then spent the night with the old friend, taking care of her.

Over the next few months, Triss spent every day with Ciri and tought her various topics, including the Elder Speech and how to apply make-up. In February 1266, as the spring neared, the witchers were slowly preparing to go on the path once again and wanted to know all the relevant news from the Continent, so as to decide where to go.

Triss told them everything she knew and they eventually talked about the possibility of a second war with Nilfgaard. This resulted in a heated debate about witchers and their neutrality on politics. Ciri ran in and interrupted the conversation, saying she wanted to kill all of the Nilfgaardians for they did to her city and grandmother Calanthe. Angered by this, Geralt told the young girl he was training her to defend herself only, not to seek revenge. Ciri ran outside and stood on the edge of the walls, tripping and nearly falling to her death, just in time for Geralt to catch her. With that, Triss and Geralt decided that with the morning light, they would go to the temple in Ellander.