Klaus was born to Lt. Cmdr. Otto Fienberg and Lt.Cmdr. Shannon O'Banyon-Fienberg, ACMO and Chief Engineer of the USS Renville respectively.

Klaus would have been a Fleet brat if it hadn't been for accident that gave his mother terminal radiation sickness. They returned to Shannon's hometown on Earth. Dublin. There Shannon lived out her final weeks. Her death was the final catalyst for Otto's retirement from Starfleet. Something he was deciding on for the last year. He was offered a position at the London medical academy as a professor, but he declined to become a local physician in his hometown, Berlin. The Main reason was that he wanted to live with and take care of his son himself, but not for him to become and english boy. He wanted a german boy.

Klaus childhood was far from the sheltered life he would have had aboard the Renville. His childhood was raw and real growing up in urban Berlin. Like his father. He was tough and intelligent. But he never started any fights. But He finished them.

Over the years and into High School, he slowly became more and more peaceful. His tough friends from his childhood days kinda didn't like it, but admired his peacefulness and respect. That kept him out of any fight he could have had in at the time. If anyone ever struck him, he would simply turn the other cheek. Again, same deal but with a warning. Third time, the guy was on the floor, or later on in life, in a headlock. At about the time of his graduation from the academy, he wouldn't even do that. His justification was "I would never stoop so low as to violence for such a petty matter."

A year after his leaving the Vulcan Medical Institute, his life changed. He was suddenly in a war. Being a doctor, he never fought, but he was always was near the battle field. He faced the horrors of war in the worst way possible (in his opinion).

He was in a direct medical support role during the Battle of DS9. One would think that was a terrible time for him. It was, but it wasn't the worst for him. The horrors of war and the death of his father on Earth, led him to the reason for his lowest point. Soon after the war ended.

His previous steady drinking habit of a harmless drink every once and, to a steady drunkenness every night. He slowly went downhill.

In 2377, aboard the USS Sturmovik-A, he reached his lowest point. The fact that the Assistant Chief Medical Officer had attempted suicide hit morale hard. Captain Savage immediately sent him to Counseling for rehabilitation. It paid off a year later. Klaus had completely dropped the bottle. He never took a single swig again. That, in his opinion, was the best time of his life.

He became romantically involved with a Counseling officer aboard the Sturmovik-A named Lacy Trang (the same one that helped through his depression and drinking problem). A half Betazoid. They were involved until about a month before Klaus' departure from the Sturmovuk-A. It was a double agreement that perhaps they should go their separate ways and find each other again someday, and continue then. They have not had contact since.

He was then transferred the USS Galaxy in 2379 to assist in the duties of the Medical Department.

Upon the departure of Dr. reynolds, Kalus was promoted to Lieutenant and Chief Medical Officer of the Galaxy in December 2381.

He is EXTREMELY peaceful. He is also the perfect Gentleman. He is a little alone in the Romantic prospect, and would like to cross paths with Lacy again, but is open to others.

Listens to Metal like a fiend, same with classical. Was in a metal band in his Academy days, and still has his 5-string electric bass. The Band's name was Die Doktoren and consisted of himself and other German's in the medical academy. They all keep in touch. One of them, the Lead drummer, was killed in the Dominion war though.

He wants to find Metal versions of his favorite Classical pieces as well.