You need to know if a user is following another user, to do this you need to look at the isFollowing property on the profile response.

This is shown in the examples when fetching back a profile. In the isFollowing field resolver you can pass in a profileId you wish to know if the owner of this profile is following, most apps would use the logged in users selected profile they are browsing on.

API design basic

please note the example below doesn't pick all the content out of the profile it just shows you the field used to get that back.

query Profile {
  profile(request: { profileId: "0x01" }) {
    isFollowing(who: "0x08")
  }
}

The profile id passed in for isFollowing can pass in as a variable easily enough as well. You can imagine passing the logged-in users profile they are browsing on to see if you should render a follows back label. This can be hooked in like this for every query which returns a profile type.

query Profile($profileId: ProfileId) {
  profile(request: { profileId: "0x01" }) {
    isFollowing(who: $profileId)
  }
}