loadVsWith.php

<?php

class Event
{
    public function fights()
    {
        return $this->hasMany(Fight::class)->orderBy('fightcard_order');
    }

    public function topFight()
    {
        return $this->hasOne(Fight::class)->orderBy('fightcard_order');
    }
}

// what's the difference

$topFight = $event->topFight()->with(['fighter1', 'fighter2'])->get();

// between

$topFight = $event->topFight->load(['fighter1', 'fighter2']);