Other alien groups, like ourselves, have been around for eons, and have an intense interest in the future of Earth, our future home. Their missions are as numerous as they themselves, as opportunity abounds. Like ourselves, they must wait for The Call from a human, and then depending upon the situation, the goals of the human, and the requested guidance from the visitor, they jointly may be of service to the Earth and its many inhabitants. The hand of the various groups can sometimes be seen in the type of endeavor undertaken by the human who gave The Call. The Sirians are more war like, have this history in their past, and take The Call from humans who could use logistical advice during confrontations.
Nordics are very scientific and intellectual, and dislike the spotlight.
They thus work behind the scenes, and their contactees are never heard of.