Not all gods are equal in power levels. Though since Jormundgand isn't a god per say, I guess it's more accurate to say not all spirits are equal in power levels.
But I do believe that you can work with both, or even have a full pathworking with one, and then move on to the other and that it's not an either/or deal, and I also agree that you should tell us why exactly these two so that we can see how to act.
However, spirits, and humans, often have magnetic relationships, in that one is specifically attracted to the other. Oftentimes, people have had guardian spirits for their whole lives, but never even heard the spirit existed, or were never too curious about them.
Happened to me with Baron Samedi and Damballa when I was way too scared to even dabble in Vodou, much less work with a Loa directly. Happened to a friend of mine with Santa Muerte, to name just a couple. At which point the spirit finds some way to come into your life.
Other times, you're so attracted to them, and other times, you're more interested in them than they are in you, though upon contacting them have one of the best business relationships.
It can be freaky at times, so do bear in mind, that it's not an exclusive deal, though why do you want to work with Skadi or Jormundgand?