2p Denmark:

Magnus refers to (y/n) with her name, sometimes dear or darling, and if he feels romantic he calls her 'Dronning'.

(Y/n) gives him different names based on his mood, but mostly calls him 'your highness' or 'My king'. As reference for him calling her his queen in his language.

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2p Sweden:

Calls her tilltugg, even though she hates that. Calls her älskling as well.

(Y/n) calls him Maneater or criminal, sometimes calls him her knight.

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2p Finland:

He does not Really do petnames. He just calls her by her given name.
Sometimes calls her his prize, and if he is feeling particularly mischievous... Narttu, Or his bitch.

She calls him her soldier, grumpy, or darling.

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2p Norway:

Loki calls her ember, his flame, or Dyrebar.

(Y/n) calls him honey, babe, or hottie.

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2p Iceland:

Egil calls her prinsessa, Kona, and any other sweet thing he can think of.

(Y/n) calls him her prince or cutie. If she is mad with him she refers to him as 'stalker'