South Italy hates his younger brother North Italy's ally Germany because he thinks he's not good for his sibling (and since both Germany and Romano are male Tsunderes.)
According to Word of God, Norway acts similarly towards Iceland. Confirmed in a strip, where Norway tries to make Iceland call him "Big Brother" (in the original, "Oniichan" an honorific that usually little kids use towards their older brothers) and strangles Denmark with his own tie when he cracks jokes about it.
All of the older Nordics act this way toward Iceland to some extent, though Norway is the most adamant about it. Denmark refers to himself as the older brother of all the Nordics. His being especially attentive toward Iceland annoys Norway.
Norway's World☆Stars Character Profile: Because Denmark also acts like he's Iceland's older brother, Norway pokes him every time he does that!
England also acted as an older brother figure to America, in his own way. The Revolutionary War thus broke his heart, and he still seems to have a soft spot for him (not that he'd ever show it).
France thinks of himself as the older brother to the European nationsnote While acknowledging Spain as his elder brother in turn, but it's subverted in that only North Italy treats him as such.
Romania feels this way toward his younger brother Moldova, to the point that he gets depressed and feels like a failure when it seems like Moldova is considering going to live with Russia.
In Hetalia World Stars 382, Malaysia is revealed to have this towards Singapore, but the latter unfortunately does not reciprocate his feelings.
