Sometimes I think the universe just waits for me to get cocky. -Dr. Egon Spengler
Dr. Egon Spengler was one of the original Ghostbusters and was known as the brains of the outfit.
Personality
Egon is the brains of the ghostbusters. He many times will save the day by coming up with ways to defeat the ghost with a different setting on the equipment. He keeps to himself mostly.
Changes Over the Seasons
Extreme Ghostbusters
As seen in Extreme Ghostbusters
Egon after being alone for years maintaining the Firehouse along with keeping Slimer there. However, the P.K.E. Meter started going off in the firehouse, and slimer took it to Egon which was at the University teachering students. Egon after getting the meter, went to the site of activity and no one believed him about the tunnel.
After tons of calls Egon decided it would be best to reopen the Ghostbusters. His role was of a mentor for the new team of Ghostbusters. For the most part, he usually leaves the field work to the new members, opting to provide audio back-up from the firehouse and information on their current adversary.
Relationship to Others
Ray Stantz
Peter Venkman
Winston Zeddemore
Janine Melnitz
Egon and Janine seem to have always been close to something more than just business. In the Ghostbusters movie there was a few moments that suggested that they may love each other. During most of The Real Ghostbusters the hints were still being thrown around in little parts in the episodes. However, the episode "Janine, You've Changed finally gave long time fans a bit of payoff, when Egon confessed that he loved her and cared about her.
In Extreme Ghostbusters, the relationship feel much like in The Real Ghostbusters. However, she feels even more like a wife or girlfriend as she cooks for him, always caring for him.
Louis Tully
Surprisingly not much to say, as they talked maybe a few times. Never argued or anything which may suggest that the cartoon may have been trying to avoid the Ghostbusters II issue of Janine and Louis relationship.
Slimer
No matter when in the show, Egon has always got along surprisingly good with Slimer. Many times Egon used Slimer to test new theories and gadgets. Egon in many ways treated him like a pet, and that was still the case during Extreme Ghostbusters.
Eduardo Rivera
Most of the time, Egon gets along with Eduardo, however there have been those days that Egon has raised his voice to him.