It seems you are trying to find an expression for two persons who followed each other (let's consider for example in twitter). I would say that this can happen for many reasons and people don't really to have a relationship in real life (i.e they don't have to like each other, or even know each other).
If the relevant message is that two persons are now following each other I would go for:
Você e o João estão seguindo-se. (You and João are following each other)
Seguir is quite common around social networks
If the relevant message is that there is a mutual retribution (they like each other twitter posts, for example) that resulted in them following each other see @Jacinto answer. I prefered his
Você é correspondido suggestion.
This expression can have the advantage of including the meaning that two persons are alike according to the 2nd definition of Priberam
Ser igual, equivaler, retribuir condignamente.
If the intent is to match two people according to their interests, like the question suggested I would go for parceiro(a):
Encontrámos um(a) parceiro(a) (We found a match/partner)
In priberam you can find the defenition of parceiro
(latim partiarius, -a, -um, que tem uma parte) adjectivo
Que tem poucas diferenças em relação a outro. = PAR, PARELHO, SEMELHANTE substantivo masculino
Pessoa ou entidade que está em parceria com outra para atingir o mesmo objectivo. = COMPANHEIRO, COMPARTE, PAR, QUINHOEIRO, SÓCIO
A pessoa com quem se joga ou dança.
[Regionalismo] Tratamento recíproco dos que foram mordomos numa festividade ou confraria no mesmo ano.
[Regionalismo] Tratamento recíproco dos pais dos cônjuges.
[Popular] Pessoa que tem esperteza. = ESPERTALHÃO, FINÓRIO
The word parceiro can be used to refer to someone that is alike (1st definition "whom that has little difference with someonelse")
Or to refer to someone that I like (2nd definition "human, or entity, that is on a partnership to reach the same goal)
It would even fit on a game, if you were developing one (3rd definition "A person to play with")