Fredrik came half way across the world, and almost killed himself to come see his father (Henrik) who was suppose to be going to Sweden, Fredrik gave Henrik the news that his best friend back in Sweden had died. Hanssen tries to tell Fredrik that he did try to board a plane to go to Sweden but couldn't as it was an odd number of seats. Fredrik was confused as to why he couldn't board in which Hanssen replied "I suffer with depression". It is revealed in Fredrik's notes that he has been taking anti-depression medication hence the reason why Hanssen told him about his diagnosis.
Fredrik later shows Hanssen the medication that was produced by the family business back in Sweden, which he thinks would cure depression, but he needs funding for the medicine to get it out throughout the counrty. Fredrik shows Hanssen a picture of his child Oskar, as he starts describing him and that he's starting to push the boundaries, he says to Hanssen that he can keep the picture of his grandson. Fedrik begs Hanssen to come home (Sweden) as he needs his father.
Fredrik is rushed to theatre after having an extensive internal bleed, due to a small tear from the operation earlier on from Isaac Mayfield. Hanssen later finds out that the anti-depression medication made by his company, was only at trial-stage. After ruining the family company, Fredrik want's Henrik to return to take it over. Henrik wouldn't sign the company certificate, but did report the faults in the medication trials to Sweden where the company will no longer be able to make trial medication again, he said he did it for Oskar's future. Fredrik has been taking anti-depression medication that his family company was producing for the trial, it turns out that he doesn't suffer from depression.
We see that, despite from his company in Sweden being banned from developing drugs, Fredrik is still developing drugs himself when he gets to Holby. In Thicker Than Water, a patient Fredrick has already met in Sweden arrives at Holby with pancreatic problems. Her arrival was planned by Fredrik, who made the sure her diagnosis and surgery were both by him, so he could try and win his Father’s backing to move to human trials with his medication by claiming that the problem in her pancreas could have been prevented had the medication Fredrik designed been available. Hanssen quickly sees that Fredrik had set the entire thing up and asks him if he had met her in Sweden, to which Fredrik looks down and says “Of course.” In a later scene it is revealed that Fredrik had coerced the patient into delaying the surgery until he was in England. His wife, who was oblivious to this plot, sees this as him endangering the patients life and sees no point in them staying in England if Hanssen will not back the trials. Sara gives him the ultimatum of staying in England or going home to Sweden with her and Oskar. Fredrik refuses to leave England, and she drives away, leaving Fredrik crying at the entrance of the hospital.
One of the most noticeable features about Fredrik is how uncomfortable he appears in his own skin. He is shown to be constantly tense, as well as seeming unused to receiving praise. He seems shocked when someone seems to genuinely believe in him, which is only accentuated by the issues he has over Hanssen's treatment of him, which seems to cause him distress.
Despite being shown with some unlikable traits that have a habit of rubbing people up the wrong way (such as his smugness, plotting nature, and generally superior nature) he still manages to gain friends, or at least fondness, in high places, impressing both Sacha and Nina on multiple occasions, enough so that Fredrik wins her backing for the Junior Doctor Award.
Contrary to what some of his more devious plans would suggest, Fredrik is hardly a sociopath, and within less than 2 months of him being at Holby, we see him crying multiple times. He seems to have have a mask he can put up when he is on the ward, however as soon as it isn't required, he will crumble. One of the most noticeable moments of this is in Nina's office, where after a day of being decidedly more snappy and harsh than usual he is dragged into her office. After an apology over how she had acted towards him earlier, he broke down and explained that Sara had left him.