select p.peak_id, pp.peak_id
from api.peak as p
join lateral (
    SELECT DISTINCT p2.*
        FROM api.peak as p2, api.peak_to_peak as p2p
        WHERE (p2p.peak_a_id = p2.peak_id OR p2p.peak_b_id = p2.peak_id) AND (p2p.peak_a_id = p.peak_id OR p2p.peak_b_id = p.peak_id) and p2.peak_id != p.peak_id
) as pp on true
where p.peak_id = 2