Few facts are known about his face. Yet, all theories stated that Guertena was either middle-aged or an old man before he died. On the recent version of Ib, a portrait of him is displayed, yet his face isn't shown; therefore, the mystery of Guertena still remains.
Very little is known about Guertena, though it seems he was a skilled and passionate artist having an entire museum for just his work alone. In fact, his work was so good that some of it came to life, implying he may have some magic in his background. This does not appear to have pleased him, as in A Painting's Demise, it's implied he keeps a close eye on the main characters and will kill them if they leave without meeting the appropriate requirements.
- In his self portrait, Guertena can be seen holding a paint brush in his left hand, which hints that Guertena might be left-handed.
- The picture that he is painting is the portrait of Mary.
Below is a list of compiled ideas and theories about the game.
- Garry is Guertena. Though this theory is just a thought, people gave this attention as they try to realize the idea.
- However, the lady in black standing near the Fusion statue in the Guertena Art Gallery mentions that Guertena is, indeed, dead.
- The book about Mary's true identity in the Violet Area mentions that the Mary painting was the last one that Guertena had painted in his life, hinting that Guertena had already passed away.
- Guertena painted Mary as a memory of his daughter or his "dream" daughter. A lot of theories stated that he based it on his painting The Lady in Red. Fans also followed this theory.
- This theory became less believable when Mary mentioned that the Lady in Red was her "sister" after a newer version of Ib was released.
- Mary could not be a memory of Guertena's daughter, as the book about her true identity in the Violet Area stated that she was not based on any real person. The man looking at The Lady in Red painting in the Guertena Art Gallery also mentioned that Guertena was known to not paint real people.
- Guertena had a past relationship with Ib. Any child with a huge imagination could enter the gallery. Why Ib? The thought came to people, trying to connect the paintings and Guertena, one by one.
- Something is wrong with Guertena himself. Despite the fact that his paintings are constantly praised, it was theorized that he had extreme emotions while painting his art. This led to the solution for why the paintings moved on their own.